Prominent theories suggest self-injurious thoughts and behaviors (SITBs) are negatively reinforced by decreased negative affect. The present meta-analysis quantifies effects from intensive longitudinal studies measuring negative affect and SITBs. We obtained data from 38 of the 79 studies (48%; 22 unique datasets) involving N = 1,644 participants (80% female; 75% white). Individual participant data meta-analyses revealed changes in affect pre/post SITBs. In antecedent models, results supported increased negative affect before non-suicidal self-injurious (NSSI) behavior (k = 14; 95% CI = 0.09 – 0.31) and suicidal thoughts (k = 14; 95% CI = 0.03 – 0.19). For consequence models, negative affect was reduced following NSSI thoughts (k = 6; 95% CI = −0.79 – −0.44), NSSI behaviors (k = 14; 95% CI = −0.73 – −0.19) and suicidal thoughts (k = 13; 95% CI = −0.79 – −0.23). Findings, which were not moderated by sampling strategies or sample composition, support the affect regulation function of SITBs.
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