A short-term longitudinal study (N = 162 undergraduate students) replicates and extends previous findings on the relationship between self-reported procrastination and behavioral measures of procrastination (i.e., a comparison between actual and planned study time), and assesses their relation with affective well-being. All variables were measured 16 times over the course of 8 weeks. State measured self-reported and behavioral procrastination correlated only moderately. In line with the definition of procrastination as a combination of delaying to work on a task and discomfort with the delay, affective well-being was better predicted by self-reported than by behavioral procrastination. This suggests that self-reported procrastination better reflects the construct than a purely behavioral measure of procrastination. Consequences and implications for further assessment of procrastination are discussed.