The purpose of this study was to develop a brief physical activity interview for older adults (Phone-FITT) and evaluate its test-retest reliability and validity. Summary scores were derived for household, recreational, and total PA. Reliability was evaluated in a convenience sample from a fall-prevention study (N = 43, 79.4 +/- 2.9 years, 51% male), and validity, in a random sample of individuals in older adult exercise programs (N = 48, 77.4 +/- 4.7 years, 25% male). Mean time to complete the Phone-FITT was 10 min for participants sampled from exercise programs. Evaluation of test-retest reliability indicated substantial to almost perfect agreement for all scores, with intraclass correlation coefficients (95% confidence intervals) ranging from .74 (.58-.85) to .88 (.8-.94). For validity, Spearman's rho correlations of Phone-FITT scores with accelerometer counts ranged from .29 (.01-.53) to .57 (.34-.73). Correlations of Phone-FITT recreational scores with age and seconds to complete a self-paced step test ranged from -.29 (-.53 to -.01) to -.45 (-.68 to -.14). This study contributes preliminary evidence of the reliability and validity of the Phone-FITT.