The Environmental Lead Proficiency Analytical Testing (ELPAT) Program, a cooperative effort of the American Industrial Hygiene Association, Centers for Disease Control and Prevention, NIOSH, and the US Environmental Protection Agency, was created to assess and improve the performance of laboratories involved with environmental lead (7439921) analysis. The program provides laboratories the opportunity to receive EPA accreditation, and is performed four times per year. To obtain accreditation a laboratory has to perform analyses of paint chip, dust and soil samples provided through ELPAT and report their findings for comparison with those of the ELPAT reference laboratories. ELPAT Round 11 was conducted in May 1995 using paint chip samples collected from North Carolina, soil samples from North Carolina and New Jersey, and dust samples obtained from household and abatement sites in North Carolina. A total of 353 laboratories submitted analytical results for Round 11, with under 7.5% of these laboratories reporting results outside acceptable limits for all analyses. The summary statistics of reference laboratories for each matrix and sample number, laboratories identified as outliers, and a summary of outliers for the lead matrices by digestion technique and analytical method used by the laboratories were presented in table form. The ELPAT Round 11 bias analysis was discussed. The certified lead reference materials used in the ELPAT Program were described and listed. ELPAT Round 12 samples were sent to participating laboratories in August 1995; the result reporting date was September 6, 1995.