Purpose: We examined the influence of parental heterosexism on in vivo negative affect and substance craving among sexual minority youth (SMY) who use nicotine and other substances, and if that relation was strengthened when in the presence of their parent(s). Methods: SMY (n 1/4 42, ages 15-19) completed baseline assessments, including experiences of parental heterosexism (PH), and a 30-day ecological momentary assessment. Ecological momentary assessment reports included affective states (i.e., anger, anxiety, depression), substance craving (i.e., nicotine, cannabis, alcohol), and other contextual factors (e.g., presence of parents). Multilevel logistic regression models evaluated the study hypotheses.Results: PH was associated with greater odds of reporting in-the-moment anger, depression, cannabis craving, and alcohol craving. Parental presence was associated with lower odds of reporting anxiety or depression, and greater odds of reporting nicotine craving. There was a significant interaction when predicting the odds of reporting anxiety. For SMY low in PH, parental presence was related to lower odds of reporting anxiety. As PH increased, parental presence had diminishing associations with the odds of reporting anxiety.Discussion: Parenting behaviors can serve as protective and risk factors for negative affect and substance craving among SMY. Improving family-based interventions for SMY may be integral for enhancing healthy development and reducing health disparities.(c) 2022 Society for Adolescent Health and Medicine. All rights reserved.