A cultural-ecological perspective elucidates how culture informs caregivers’ beliefs and values, as well as their caregiving behaviors in response to their children’s emotions. In infancy and toddlerhood, caregivers are responsible for externally regulating their children’s emotions and physiology through their behavioral responses to children’s arousal. Yet, little has been documented about the cultural values and emotion socialization behaviors of Mexican American mothers at this important time for caregiver-child interactions. The overarching goals of this dissertation were to explore (a) Mexican American mothers’ cultural values, (b) mothers’ behavioral responses to toddlers’ difficult emotions (e.g., sadness, fear, anger), and (c) associations between cultural values and emotion socialization behaviors using quantitative data from bilingual English/Spanish interviews with Mexican American mothers. Paper 1 describes Mexican American mothers’ cultural values (i.e., familismo, respeto, religion, traditional gender roles, independence/self-reliance, competition, material success) and applies culturally informed theorizing to understand within-group differences in cultural values based on cultural (i.e., generational status, enculturation, acculturation) and minority status factors (i.e., education, discrimination, and economic hardship). Paper 2 describes how mothers react to their toddlers’ difficult emotions with their supportive or nonsupportive responses and examines associations between Mexican American cultural values (e.g., familismo, respeto, religion, traditional gender roles, and independence/self-reliance) and mothers’ emotion socialization behaviors. These two papers are intended to make meaningful contributions by integrating a culturally informed framework to understand Mexican American mothers’ beliefs and behaviors, in context, at a fundamental time in their children’s development.