Given the situation where research attention targeted at toddler group was relatively small, this study aimed to investigate relationships between toddlers’ emotion regulation abilities and adjustment in daycare center. Considering the previous findings suggesting that toddler age and gender could affect their adjustment in daycare center, this study included toddler age (months) into correlation and regression analyses and administered these analyses for each toddler gender. Participants were 189 toddlers (91 male and 98 female, mean age of 30.16 months old) from 10 daycare centers located in Seoul metropolitan area. Toddlers’ emotion regulation abilities and adjustment in daycare center were measured using the Toddler Emotion Regulation Abilities Scale(Kim, 2011) and the Preschool Adjustment Questionnaire (Jewsuwan, Luster, & Kostelink, 1992). Correlations analyses among toddler age, three emotional regulation abilities dimensions (emotion recognition/expression, emotion management, and emotional coping) and five adjustment indices (adjustment to routines, peer relationships, positive emotions, ego strength, and prosocial behaviors) revealed mostly similar relationship patterns but gender differences in the relationships between toddler age and four adjustment indices and between emotion recognition/expression and prosocial behaviors. Next, hierarchical regression analyses were conducted for each of the five adjustment indices with the step 1 entering toddler age and step 2 entering three emotion regulation abilities. Results suggest that three emotional regulation abilities significantly incremented explanation for the variance in each of the five adjustment indices. Emotion management, and emotional coping seemed to be particularly important in predicting these adjustment indices, regardless of toddler gender. Gender difference in the effects of emotion regulation abilities were found only in the prediction of ego strength and prosocial behaviors. In the prediction of ego strength, only emotional coping was significant in male, but both emotional coping and emotion management were significant in female. Noticeably, emotion management abilities were found to have negative effects on toddler ego strength. In the prediction of prosocial behaviors, all the three emotion regulation abilities were significant in female but only two (emotion recognition/expression, emotion management) were significant in male. Results were interpreted and clinical implications of the findings were discussed.