Background: Self-reported cancer screening behaviors are often overreported and may lead to biased estimates of prevalence and of subgroup differences in screening. We examined whether the tendency to give socially desirable responses was associated with concordance between self-reported colorectal cancer (CRC) screening behaviors and medical records. Methods: Primary care patients (n = 857) age 50 to 74 years completed a mail, face-to-face, or telephone survey that assessed CRC screening and social desirability measured by a short version of the Marlowe-Crowne scale. We used medical records to verify self-reports of fecal occult blood testing (FOBT), sigmoidoscopy, colonoscopy, and barium enema. Results: Social desirability scores were lower for whites versus African Americans, college graduates, and patients reporting no prior screening tests; they were higher for telephone versus mail or face-to-face survey respondents. In univariable logistic regression analysis, social desirability scores were not associated with concordance for FOBT (OR = 1.03, 95% CI = 0.94-1.13), sigmoidoscopy (OR = 0.95, 95% CI = 0.86-1.04), or colonoscopy (OR = 0.99, 95% CI = 0.88-1.11); however, lower social desirability scores were associated with increased concordance for barium enema (OR = 0.87, 95% CI = 0.77-0.99). In multivariable analyses, no associations were statistically significant. Conclusion: Social desirability as measured by the Marlowe-Crowne scale was not associated with accuracy of self-reported CRC tests in our sample, suggesting that other explanations for overreporting need to be explored. Impact: By understanding sources of response bias, we can improve the accuracy of self-report measures.