<p>Previous research has demonstrated that parents’ perceived support from their social environments, including family members and friends, is critical for parental well-being and parent-child relationship qualities. However, few studies have examined the unique associations of both family and friend support with parent-child relationship qualities during early childhood and the possible underlying mechanism. Using two waves of questionnaire data from 949 Chinese parents (88% were mothers; 62% were aged 31–40 years) of kindergarten-aged children (47% were girls; the mean age at Time 1 was 4.80 years) living in Hong Kong, China, this study examined (a) whether family and friend support were uniquely associated with changes in parent-child closeness and conflict over 6 months and (b) whether these longitudinal associations were mediated by parental social functioning—parental ability to fulfil social roles as spouses, parents, workers, and individuals. Path analysis revealed that both family and friend support were uniquely associated with higher levels of parental social functioning, which in turn were associated with increases in parent-child closeness and decreases in parent-child conflict. Findings underscored the unique contributions of family versus friend support and the theoretical importance of considering parental well-being in understanding the link of social support with parent-child relationship qualities. Findings also highlighted the potential utility of targeting both family and friend support and parental social functioning as means to promote positive parent-child relationships.</p>