This study examined whether child temperamental approach reactivity moderated the association between 2 factors, parenting and child control capacities and child emotional self-regulation. Participants (N ϭ 113) were 3-and 4-year-olds (M ϭ 48 months, SD ϭ 5.78) and their mothers. Emotional self-regulation was measured as observed persistence and frustration and as maternal report of compliance. Parental approach, avoidance, control, and warmth were observed during play and a frustrating wait. Child approach reactivity and control capacities (inhibitory control and soothability) were assessed via maternal report. Results suggested that maternal approach during the wait was associated with persistence and frustration, whereas maternal warmth during the play was associated with compliance. These effects, and those of child control capacities, depended on the level of child approach. The implications of reactivity-control interactions and parent-child goodness-of-fit for emotional selfregulation are discussed.Keywords: emotional self-regulation, approach/avoidance, goodness-of-fit, reactivity and control process interactions During the preschool years, advances in several core capacities transform children's behavior and emotion. Of these, emotional self-regulation is one of the most crucial. It reflects the ability to initiate behavioral and emotional changes during emotionally charged situations in order to meet goals and manage arousal and predicts current and later adjustment (Denham, 1998;Kopp, 1982;Saarni, 1999;Shoda, Mischel, & Peake, 1990). In early childhood, persistence during challenges, frustration tolerance, and compliance with caregiver demands are hallmarks of successful emotional self-regulation (Eisenberg et al., 2001;Kochanska, 1993).Findings from diverse disciplines in psychology suggest that emotional self-regulation emerges out of the interplay between two powerful sets of influences: reactivity, or arousability of physiological, emotional, and behavioral systems, and control processes, or modulation of reactivity to meet goals (Carver, Sutton, & Scheier, 2000;Derryberry & Rothbart, 1997;Davidson & Fox, 1989;Davidson et al., 2002;Fox, 1994;Posner & Rothbart, 2000). Among the most fundamental dimensions of reactivity are approach and avoidance in response to novel, unfamiliar, and challenging situations. Approach reflects sensitivity to rewards, emotional exuberance and excited anticipation for pleasurable activities, and behavioral approach to novelty and challenge. In contrast, avoidance reflects sensitivity to potential threats, fear and shyness, and behavioral withdrawal and inhibition in response to novelty and challenge (Carver, 2004;Derryberry & Rothbart, 1997;Kagan, 1999;Panksepp, 1998). Approach and avoidance likely represent separable but interacting systems rather than a continuum of reactivity, given evidence of distinct neurological and psychological underpinnings (e.g., Coan, Allen, & HarmonJones, 2001;Davidson, 2000;Derryberry & Rothbart, 1997;Fowles, 1994;Fox, 1994;Gray & McNaught...