The capacity to regulate one's emotions and engage in prosocial behavior is vital to personal development, from infancy through adolescence. Substantial research suggests that early difficulties with emotion regulation often place children on a developmental trajectory leading to some degree of functional impairment and poor social skills. However, little is known about how interactions between parents and their children, as well as individual child and parent characteristics, impact early social and emotional development. The current study aimed to address this gap, and sought to extend the current knowledge base by also investigating how these processes vary across cultures. The study used data from the Early Childhood Longitudinal Study, Birth Cohort (N = 5055) to examine a model of the mechanisms through which child characteristics and parent behaviors throughout the early childhood period impact children's development of social skills upon kindergarten entry. Results of sequential equation model analysis provided some support for the hypothesized model, wherein lower levels of child and parent negativity and higher levels of attachment security and parent emotion support were related to higher levels of social skills as rated by parents at kindergarten entry. Additional analyses highlighted differences in the way these factors function to impact social skills development across White (n = 1900), Black/African-American ( n = 800), Hispanic (n = 300), and Asian groups ( n = 600). Findings suggest that some factors, such as parent negativity, was significantly related to lower levels of social competence in Black/African-Americans, but had little impact on social skills development in the other groups studied. Furthermore, results indicated a positive relationship between child negativity in preschool and social competence at kindergarten entry for Asians. The importance of these and other results are discussed in light of extant literature, implications that may have affected results, and directions for future research.