This report reviewed the steps in the evaluation program for laboratories participating in the Environmental Lead Proficiency Analytical Testing (ELPAT) Program. The first step was to identify the sample analytical results for lead (7439921) in paint chips, soil and dust reported by a preselected group of reference laboratories. All laboratories had to be recognized by the Environmental Protection Agency's National Lead Laboratory Accreditation Program (NLLAP), which required that the laboratory performed well in the previous round of the ELPAT Program required recognition (each round was for one quarter of the year), and was accredited by an NLLAP recognized laboratory accreditation organization. Step two was the treatment of reference laboratory data which was inconsistent with the rest of the data. The final step was the calculation of the reference laboratory means and standard deviations using data from step two. After the acceptable ranges were calculated, the data from all participating laboratories, including the reference laboratories, were compared with permissible ranges to determine their acceptability. Laboratories were rated on individual lead matrix performance. Individual lead matrix performance was rated as proficient, proficient if all results were reported and all were classified as acceptable for the last two consecutive rounds, or proficient in all other situations if three quarters or more of the results reported in the last four consecutive rounds were acceptable. Participation in ELPAT was not designed to replace internal quality control programs for laboratories.