The present study aimed at examining the effects of mothers' psychological well-being, parenting style, and home environment on toddlers' peer relationships. The study analyzed 800 families who participated Korean Child Panel Study the 4th wave and had data of teacher-rated peer relationship of the child. Mean age of the 800 children was 38.24 months old. The analysis of structural equation modeling revealed that mothers' psychological well-being significantly predicted more social parenting style and richer home environment of the toddlers. When the child’s home environment provided greater cognitive and language stimulation and sensitivity, the child was less likely to show aggression and withdrawal during peer relationship at child care settings. The direct path from parenting style to peer maladjustment behaviors was not significant. Rather, mothers' more social parenting style predicted better quality of home environment, which in turn, predicted less aggression and withdrawal in peer relationship among the toddlers. The results shed lights on the importance and need of parent-support program that can help mothers to alleviate depression and stress and improve self efficacy.