Ecological momentary assessment is increasingly leveraged to better understand affective processes underlying substance use disorder treatment and recovery. Research in this area has yielded novel insights into the roles of mean levels of positive affect (PA) and negative affect (NA) in precipitating drug craving and substance use in daily life. Little of the extant substance use disorder treatment research, however, considers dynamic patterns of PA and NA, separately or in relation to one another, or how such patterns may differ from those observed among nonclinical samples. The current ecological momentary assessment study examined between-person differences in within-person affect dynamics-including intensity, variability, instability, inertia, polarity, and spillover-among patients in residential treatment (