<p>A growing body of research has sought to understand the contextual factors that influence emotion regulation (ER) strategy choice. As a process that is usually involuntary to start and difficult to end, perseverative thought (PT) can be an ongoing context that influences how individuals respond to emotions. This study investigated how different PT dimensions, captured through written language, predicted subsequent ER strategy choice, including engagement (i.e., reappraisal, acceptance, problem-solving) and disengagement (i.e., experiential avoidance, distraction, expressive suppression) strategies. College students (<i>N</i> = 413) completed an experimental paradigm once a day for ten days. Each night, they underwent a PT induction writing task and were instructed to regulate (to feel better) and report their ER strategy use (1 = selected; 0 = not selected). We used the Linguistic Inquiry Word Count program to construct PT dimensions and multilevel logistic regressions to examine links between each PT dimension and subsequent ER strategy selection. Within individuals, higher negative valence during PT predicted a higher likelihood of selecting distraction. Higher self-focus during PT predicted a greater likelihood of selecting experiential avoidance and expressive suppression. Higher situation certainty, more social words, and more past focus during PT predicted a lower likelihood of selecting problem solving. Overall, the findings support the role of PT dimensions as important contextual features for ER strategy selection and highlight the value of computational linguistics and a dimensional approach for studying PT.</p>