<p>Both obsessive thoughts and an urge to act have been linked to compulsions cross-sectionally. However, prominent theories of compulsivity disagree quite fundamentally about whether compulsions are goal-oriented attempts to reduce or eliminate obsessive thoughts or are urge-driven and habitual. To shed light on this debate, we used multilevel vector autoregression modelling to analyse contemporaneous and temporal associations based on self-report symptoms and cognition from <i>N</i> = 179 individuals with and without diagnoses who performed compulsions. Six weeks of three-times daily timeseries data with a mean lag of five hours between assessments were gathered from a transdiagnostic sample who checked their phone compulsively, binge ate, or engaged in compulsions commonly seen in OCD (e.g. checking, cleaning). Across compulsions, the strongest within-person correlate of compulsions were urges (β = 0.61, p_FDR &lt; 0.001) and this was 3 times larger than obsessive thoughts and 4 times larger than anxiety. We found that urges predicted compulsions at the next assessment time point (β = 0.09, p_FDR &lt; 0.001), while compulsions themselves had a markedly low tendency to predict themselves (β = 0.04) compared to the other mental health symptoms sampled (0.12 &lt; β &lt; 0.23). Finally, like habits, compulsions occurred more often when executive functioning was low (β = 0.09, p_FDR &lt; 0.001). Based on real-time dynamics of compulsions, we find that urges, but not obsessive thoughts, predict compulsivity five hours later. Intriguingly, the associations were remarkably similar across compulsions, supporting the notion that transdiagnostically, a habit-like mechanism may underlie compulsive actions.</p>