Depressive disorders can be observed in early childhood and are associated with significant concurrent and prospective impairment; however, little is known about day-to-day variations in common depressive behaviors in children. This study examined the day-to-day variability of two common depressive behaviors in preschool-aged children, sadness and irritability, and factors associated with the daily occurrence of these behaviors. Participants included 291 parents of preschool-aged children, and parents completed a 14-day daily diary. Results indicated that sleep quality did not prospectively predict next-day sadness or irritability the following day. We observed between-person stability, but within-person variability, in children’s sadness and irritability across 14 days. We observed greater between-person stability and greater within-person variability in sadness and irritability for males and for children with fewer baseline psychiatric symptoms and lower baseline impairment. Findings provide a developmental perspective on normative patterns of sadness and irritability in young children and can inform prevention and individualized intervention efforts to reduce negative sequelae in at-risk preschoolers.