Temperament, appraisal, and coping are known to underlie emotion regulation, yet less is known about how these processes relate to each other across time. We examined temperamental fear, frustration, effortful control, and impulsivity, positive and threat appraisals, and active and avoidant coping as processes underpinning the emotion regulation of pre-adolescent children managing stressful events. Appraisal and coping styles were tested as mediators of the longitudinal effects of temperamental emotionality and self-regulation on adjustment using a community sample (N = 316) of preadolescent children (8–12 years at T1) studied across 1 year. High threat appraisals were concurrently related to high fear and impulsivity, whereas effortful control predicted relative decreases in threat appraisal. High fear was concurrently related to high positive appraisal, and impulsivity predicted increases in positive appraisal. Fear was concurrently related to greater avoidant coping, and impulsivity predicted increases in avoidance. Frustration predicted decreases in active coping. These findings suggest temperament, or dispositional aspects of reactivity and regulation, relates to concurrent appraisal and coping processes, and additionally predicts change in these processes. Significant indirect effects indicated that appraisal and coping mediated the effects of temperament on adjustment. Threat appraisal mediated the effects of fear and effortful control on internalising and externalising problems, and avoidant coping mediated the effect of impulsivity on internalising problems. These mediated effects suggest that one pathway through which temperament influences adjustment is pre-adolescents' appraisal and coping. Findings highlight temperament, appraisal, and coping as emotion regulation processes relevant to children's adjustment in response to stress.