This longitudinal study examined developmental trajectories of infant sleep problems from 3 to 24 months old and investigated associations with infant-parent attachment security and dependency. In a sample of 107 Israeli families, number and duration of infant nighttime awakenings were measured at 3, 6, 9, and 24 months old, using mothers' and fathers' reports on the Brief Infant Sleep Questionnaire (BISQ). Infant-parent attachment security and infant-parent dependency was assessed at 24 months old, using the observer Attachment Q-Sort procedure (AQS) with both parents. Latent growth curve models showed a non-linear decline in number and duration of infant nighttime awakenings over time. A higher number and longer duration of infant nighttime awakenings at 3 months were associated with higher infant-father attachment security at 24 months. In contrast, longer infant nighttime awakenings at 3 months were predictive of lower infant-mother attachment security at 24 months. A steeper decrease in duration of infant nighttime awakenings was associated with higher infant-father attachment security and lower infant-mother attachment security. As a potential mechanism, paternal involvement in nighttime caregiving was explored in relation to infant-father attachment security. Results of our post-hoc analyses revealed no significant associations between paternal involvement in nighttime caregiving and infant-father attachment security. Our results highlight the need to examine potential mechanisms explaining the divergent associations of infant sleep problems with infant-mother and infant-father attachment security in future research.