Across three studies, we use behavioral measures of task delay to demonstrate that valence weighting bias predicts the extent to which individuals delay initiating a task, particularly when they lack the motivation and/or opportunity (e.g., mental resources) to deliberate on their initial appraisals of situations. Study 1 revealed that people with a more negative weighting bias delayed submitting tax returns to a greater extent. In Study 2, students with a more negative weighting bias delayed more as they earned course credit as part of a research experience program, with this relation being all the stronger among those low in trait self-control. Finally, Study 3 provided causal evidence for this relation: within a sample of students recruited for their procrastination, shifting the valence weighting tendencies of the strong procrastinators toward a more neutral, objectively correct point led to less delay in the context of participation in a research experience program.