Suicidal ideation and behavior, non-suicidal self-injury, and impulsive aggression are highly prevalent in autistic adults. These difficulties are proposed to arise from emotion dysregulation (ED), including problems flexibly up- regulating or sustaining positive valence systems or down-regulating negative valence systems. However, there is limited prior research on ED among autistic adults. Findings from the scant prior studies on emotional reactivity and regulation in autism have been mixed, including evidence of patterns of both hyper- and hypo- reactivity across multiple response systems (i.e., physiology, behavior, and self-report), which may vary as a function of individual differences and context. Despite the clinical significance of ED for autistic adults, how and why ED manifests in autistic adults and the significance of either hyper- or hypo-reactivity for real-life functional outcomes remain poorly understood. To address these gaps, we will assess ED using a 14-day ecological momentary assessment protocol with continuous ambulatory monitoring of parasympathetic and sympathetic nervous system activity in a sample of 200 autistic adults and 100 non-autistic adults (both groups oversampled for suicidality). Specifically, we will characterize how ED emerges in a variety of contexts across response systems (i.e., subjective, behavior, physiology) in daily life, and how ED components may dynamically contribute to proximal risk for subsequent suicide ideation, self-injury, and impulsive aggression as a function of both autism and suicidality history. Findings will reveal aspects of ED that are unique to autism versus those that are common across autistic and non-autistic individuals at risk for suicide. Our cross-project integrative aim will identify individual and subgroup patterns of ED processes that characterize distinctive risk groups. Linking ED components to real-world outcomes of clinical significance using physiologically-triggered EMA will allow us to characterize and evaluate the functional significance of different patterns of ED components and identify near-term risk and resilience processes in a temporally sensitive manner. Findings will lead to novel treatment targets and just-in-time intervention strategies prior to onset or escalation of ED and associated deleterious outcomes.