Repeated positive and negative affect measurements are widely administered to adults in Turkey in both empirical and clinical work. However, within-person reliability of these measures has never been tested. Test-retest coefficient, a traditional index of reliability, does not evaluate within-person reliability and therefore, an investigation regarding the assessment of both within and between person reliability for repeated measures of positive and negative affect is crucial. The present paper examines the within-person reliability of the widely used Positive and Negative Affect Schedule (PANAS) in Turkish context. Two data sets were included. The first study included 196 participants, with three weeks' time interval at four time points. The second study included 41 participants, with one week time interval at thirteen time points. Within person reliability was calculated via the method recommended by Cranford et al. (2006). In the first study within-person reliability for Positive Affect was found as.80, and for Negative Affect as.79. In the second study, within-person reliability for Positive affect was found as.86, and for Negative Affect as.87. Furthermore, between-person reliability indices were calculated for each study. The PANAS had satisfactory within and between-person reliability coefficients in both studies.