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U.S. Department of Health and Human Services

Archival Content: 1999-2005

HIV Prevention Among Drug Users:
A Resource Book for Community Planners & Program Managers

Theories of Behavior and Behavior Change

The Role of Theory in Planning Interventions

Early in the epidemic, prevention planners assumed that a greater awareness of the factors involved in HIV transmission would more likely result in the adoption of HIV prevention behaviors. It is now known that HIV prevention efforts cannot rely solely on providing risk information. Other factors also must be addressed. Theory can help identify these additional social, psychological, and cultural factors and can help planners decide which factors need to be addressed for which populations. Social and behavioral science theory helps clarify the reasons why people behave as they do, and it gives planners a framework for the goals and components of an intervention. This is particularly true in situations where planners have little empirical information from evaluated HIV prevention interventions to indicate which approaches are likely to be effective.

The more that is known about the factors that influence whether or not a person will engage in a behavior, the more successful prevention planners and program managers can be at selecting an intervention that effectively influences that behavior. Social and behavioral theory, and testing this theory in HIV prevention interventions, can help identify more specifically the factors that programs need to address to facilitate behavior change.

In fact, prevention planners and program managers regularly use behavioral theory. Because HIV is largely transmitted through behavior-sexual and drug-using-planners and managers know that they must promote behavior change. They are familiar with at-risk populations in their communities, and often have an intuitive understanding of what characteristics and circumstances of their target populations influence their risk behaviors. By using social and behavioral theory and research, planners and managers can verify much of their practical experience, challenge certain assumptions, and, overall, have a firmer scientific foundation for selecting and designing effective interventions. In short, the use of behavioral science can help improve programs, increase effectiveness, and save valuable time, resources, and lives.

Some Important Theories and Approaches

Theoretical approaches identify different sets of factors to explain HIV risk behavior change. This section reviews several theoretical approaches that are commonly used to explain and influence behavior and behavior change related to HIV prevention. These theories lay out factors thought to influence behavior and behavior change, principles about how these factors are related, and methods for measuring these factors.

Major behavior change theories

Of the many different theories of human behavior, three have been used frequently in behavioral and social science research on the prevention of HIV infection. The Health Belief Model (Rosenstock et al., 1994) from health education focuses on four key health beliefs that are necessary to produce a readiness to act. The Theory of Reasoned Action (Fishbein et al., 1989) is a social psychological approach dealing with the relationships among beliefs, attitudes, intentions, and behaviors. Social Cognitive Theory (Bandura, 1994) is rooted in cognitive learning theory and clinical psychology.

Fortunately for program planners and managers attempting to select among interventions, there is a significant overlap and consistency among these theories. Eight basic or common factors have been identified as points of consensus among the theorists (Fishbein et al., 1993). These eight factors, which were summarized in a National Commission on AIDS 1993 report (see Table 3.1), have been shown empirically to account for or explain most of the variation in the ways that individuals act out a given behavior. An effective intervention will influence one or more of these common factors.

Table 3.1: Eight Common Theoretical Factors


The Individual at Risk Must

Expected Outcomes (attitude)

Believe the advantages of performing the behavior (the benefits) exceed the disadvantages


Have formed a strong positive intention or commitment to perform a behavior


Possess the skills to perform a behavior


Be confident that he/she can perform a behavior


Believe that the performance of a behavior will more likely produce a positive than a negative emotional response


Believe that the performance of a behavior is consistent with his/her self-image

Perceived Social Norms

Perceive greater social pressure to perform a behavior than not to perform it


Experience fewer environmental constraints to perform a behavior than not to perform it

Source: National Commission on AIDS,1993.

The stages of behavior change approach

Along with addressing the factors that influence behavior, prevention planners and program managers may want to use a model that proposes that behavior change occurs in stages (Prochaska et al., 1992). Called the Transtheoretical Model, this approach assumes that individuals start with no intention to change, form weak intentions, strengthen these intentions, try the behavior inconsistently at first, and then finally adopt the new behaviors as a routine part of their lives. The model also accounts for those individuals who successfully progress through all five stages of behavior change, but who may relapse back to previous stages and engage in harmful behaviors again. Table 3.2 describes the five stages of change. According to this model, designing an effective intervention is a matter of determining where an individual is on the continuum of behavior change and choosing an intervention that moves him or her to a subsequent, more advanced stage.

The eight common theoretical factors reviewed earlier and stages of behavior model change work well together because the various theoretical factors can be used to move persons from stage to stage in their behavior change. For example, to motivate individuals at the pre-contemplation stage to form intentions to change behavior, an intervention might first create a perception of risk in order to alert them to the potential danger of not changing. For individuals at the preparation stage who have formed an intention to change behavior, an intervention might try to increase their confidence or, "self-efficacy," in performing a safe or safer behavior.

Table 3.2: Stages of Behavior Change


Individuals in this stage have no intention to change behavior in the foreseeable future, are unaware of the risk, or deny the consequences of risk behavior.


Individuals are aware that a problem exists, are seriously thinking about overcoming it, but have not yet made a commitment to action.


Individuals intend to take action in the near future and may have taken some inconsistent action in the recent past.


Individuals modify their behavior, experiences, or environment to overcome their problems; the behavior change is relatively recent.


Individuals work to prevent relapse and maintain the behavior change over an extended period of time.

Source: Prochaska et al.,1992

Social-level approaches

As reviewed in PART 2, risk behaviors among drug users occur between individuals and are influenced by the larger social context of social networks, family and friends, the immediate community, and the society as a whole. Although some individuals inject or use drugs by themselves, others use drugs in small groups in specific physical or social settings. The settings in which sexual activity and drug risk-taking occur can be closely related to users' social environment and participation in social networks.

Social- and community-level approaches to behavior and behavior change address the behavioral risk of individuals in the context of their personal networks and social environments. Although there is no existing synthesis of social-level theories, the Institute of Medicine convened a workshop in 1995 to begin to look at the research and program contributions of a broad set of approaches and models (IOM, 1995). Table 3.3 briefly describes four social-level approaches that emerged from the workshop.

Table 3.3: Social-Level Approaches

Diffusion Theory

Focuses on the processes by which an idea or practice is spread throughout a social system from person to person by way of particular channels of communication.

Leadership Models

Considers how naturally occurring leaders within groups can be encouraged to exhibit and communicate about an innovation or practice to their peers and the people they influence.

Social Movement/
Mobilization Theory

Describes how a culture's institutions, experiences, or characteristics can be changed by social movements begun by members of that culture.

Social Network Theory

Focuses on the relationships or interactions between two or more people or the linkages among people in a given group.

Source: Prochaska et al.,1992

Harm reduction approach

Another widely discussed concept, the "harm reduction approach," focuses on IDUs and their behaviors related to sharing injection equipment. Harm reduction acknowledges that drug users vary in their readiness and ability to abstain from drug use totally (Des Jarlais et al., 1993).This approach suggests that, based on the ways in which HIV is transmitted, some ways of engaging in drug use may be less prone to viral transmission than are others. Advocates of harm reduction propose multiple complementary solutions that operate simultaneously, including drug abuse treatment, non-injection of drugs, and providing sterile injection equipment and/or materials to disinfect used equipment.1

Using Theory to Plan and Design Effective Interventions

To help prevention planners and program managers achieve a more practical understanding of the use of behavioral theory, the following section provides concrete examples of how the theoretical approaches can form the basis for effective behavioral interventions. In addition, Appendix B of the HPDU Resource Book summarizes resources that address behavioral research and the underlying theoretical basis for behavioral interventions with drug-using populations. Reviewing these resources will give prevention planners and program managers a more comprehensive understanding of how to assess and design more effective interventions.

The AIDS Community Demonstration Projects

Exhibit F illustrates how various theoretical approaches to behavior change can be used to design effective interventions for drug users. The CDC-funded AIDS Community Demonstration Projects (ACDP) were community-level HIV prevention programs targeting several ethnically diverse, high-risk, hard-to-reach populations, including drug users (CDC, 1996). Using a common research and intervention protocol, researchers in five cities designed and implemented a theory-based community intervention that incorporated elements of the Health Belief Model, the Social Cognitive Theory, and the Theory of Reasoned Action. More specifically, the theoretical premise of the intervention assumed that four factors may influence an individual's intentions and behaviors:

  • the individual's perception that he/she is personally susceptible to acquiring HIV disease
  • the individual's attitude toward performing a low-risk behavior (e.g., consistent condom or bleach use), which is dependent on his/her beliefs about the positive and negative consequences of engaging in the low-risk behavior (expected outcomes)
  • the individual's perception that the community and peer norms toward low-risk behaviors are positively changing and thus support his/her effort to change (perceived social norms)
  • the individual's belief that he/she can effectively perform low-risk behaviors under a variety of circumstances (self-efficacy)

Exhibit F: CDC's AIDS Community Demonstration Projects


Program Activities:

Factors Influencing Individual Behavior

Distribution of small media material (newsletters, brochures, pamphlets, flyers, or baseball cards) that included:

Perceived susceptibility to acquiring HIV disease

Perceived positive and negative outcomes

Perceived supportive community and peer norms

Perceived self-efficacy

  • Role model stories or authentic stories in target group language that described a person's motivation for considering or initiating behavior change, the type of change begun, how barriers to change were overcome, and that reinforced positive consequences of change
  • AIDS information
  • Instructions on the effective use of condoms or bleach to clean needles
  • Biographies of community members participating in the project
  • Notices of community events
  • Information on other health and social services (e.g., food provision, mammogram screening, drug and alcohol treatment)

Environmental Constraints

Provision of free condoms and bleach

Stages of Behavior Change

Distribution of role model stories in the community that were designed to address the stage of behavior change of the target group (community members' stage of change was assessed before development and distribution of role model stories)

Social-Level Approaches (e.g. Diffusion Theory and Leadership Models)

Use of peer volunteers from the local community who were trained to reinforce acceptance of, and attention to, the intervention messages, as well as attempts to change behavior

In addition, the theoretical framework of ACDP included the Transtheoretical Model by recognizing that the individuals in the intervention would be at different stages of behavior change and thus would require different intervention approaches.

In laying out the theoretical framework for the interventions, the planners acknowledged the importance of barriers to behavior change, or environmental constraints. That is, for example, people might not be able to act on their intentions if condoms and sterile injection equipment were not available, readily accessible, or affordable.

Interventions using the social-level approach to behavior change

As reviewed earlier, social-level approaches include diffusion theory, leadership-focused models, social network theory, and social movement/community mobilization theory. Several interventions for drug-using populations have used principles of diffusion theory in which material or new practices are spread to the members of a social system through person-to-person channels. For example, one outreach program in San Francisco used a word-of-mouth educational program for drug injectors that promoted the use of bleach to decontaminate syringes. The program grew to include the distribution of bleach by outreach workers, who facilitated the dissemination and acceptance of the innovation (Institute of Medicine, 1995).

Leadership models encourage naturally occurring group "leaders" to model and talk about a new practice to their peers. Since the practice may depart from the group's established social norms, these models often rely on making risk-reduction strategies socially acceptable, or normative, within the target population. The National AIDS Demonstration Research/AIDS Targeted Outreach Model (NADR/ATOM) projects used this behavioral theory in the naturally occurring social structure of injecting drug users. In one of the projects, ex-addicts, under the supervision of trained ethnographers, conducted outreach to injection drug users not in treatment. Specific efforts were made to enroll influential persons ("indigenous leaders") within drug-using networks into the project, and have them act to influence other injection drug users to practice safer injection (Wiebel et al., 1996; Wiebel, 1993).

Social network theory focuses on the social networks of drug users as a unit of intervention to reduce risky behaviors and infection levels.2 Knowledge of existing social networks within a community can help determine the most effective channels of communication among network members and identify key "gatekeepers" to act as a main link to the network's membership. One example of the use of social network theory is an HIV prevention intervention in Baltimore, in which injection drug users were asked to recruit members of their networks to attend a multi-session workshop on HIV prevention and to take part in a group discussion and decision on how the intervention would address the issues of HIV and AIDS. They also discussed ways that the intervention could support individual members' decisions to alter their risk behaviors (Latkin et al., 1995).

Social movement/community mobilization theory describes how social movements initiated by members of the community change that community's representations, institutions, or experiences. This is an important strategy because local involvement is needed to implement changes necessary for improving the health of the community. This theory was used in one of the NADR projects that promoted "self-organization" among injecting drug users. Outreach workers recruited IDUs and assisted them to develop self-help groups to address HIV transmission and other issues of importance to them. Participants held regular group meetings to discuss how they could change peer norms about injection and sexual risk behaviors (Friedman et al., 1993). This theory was also used in an intervention in Baltimore that built on the power and influence of a community-based publication. For a number of years, Street Voice, a drug-users' organization composed primarily of African Americans, has published a street newsletter. The newsletter was used as an intervention vehicle to discuss HIV-related issues and changes in local treatment programs or welfare rules, and to share articles in which users talked about their lives (Institute of Medicine, 1995).

Interventions that use the harm reduction approach

Syringe exchange is the standard harm reduction method for preventing HIV infection among IDUs. In these programs, IDUs can exchange their used needles and syringes for new, sterile injection equipment at no cost. By collecting the used injection equipment, syringe exchange program managers also provide for safe disposal of potentially HIV-contaminated equipment. Because the exchange is conducted in person, the program can also deliver other services to IDUs. Syringe exchange programs typically provide AIDS education and counseling, distribute condoms (to prevent sexual transmission of HIV), make referrals to drug abuse treatment and other medical and social services, and distribute bleach for disinfecting injection equipment and/or alcohol swabs to reduce the likelihood of IDUs developing abscesses and other infections. They vary in their location (fixed versus "roving" sites), hours of operation, and the number of syringes allowed for exchange. It is estimated that over 100 syringe exchange programs have been implemented nationwide (Vlahov, 1997).

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  1. The harm reduction approach is discussed in more detail in PART 4: PUBLIC POLICY ISSUES.
  2. Social networks are described in greater detail in PART 2: DRUG USE, SEXUAL BEHAVIOR, AND HIV RISK, in the section entitled "Social Contexts that Increase HIV Risk."

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