Prior research indicates that closely spaced births are associated with poor outcomes for the mother and subsequent child. Limited research has focused on outcomes for the index child (the child born immediately prior to a subsequent child in a birth interval). The objectives are to assess the association of short birth intervals in at-risk families with: (1) indicators of harsh and neglectful parenting behaviors towards the index child, including substantiated maltreatment reports across 6 years; and (2) the index child's behavior and development in first grade. This is a longitudinal study of 658 women screened to be at-risk for child maltreatment. Twenty percent of women had a rapid repeat birth (RRB), defined as the birth of a subsequent child within 24 months of the index child. Generalized estimating equations, survival analyses, and linear and logistic regression models were used to assess the associations between RRB and index child outcomes. Women with an RRB were more likely than those without an RRB to report neglectful parenting of the index child. Children of mothers with an RRB were more likely than children of mothers without an RRB to have more behavioral problems and lower cognitive functioning in first grade. This study is among the first to focus on the associations of birth spacing with maltreatment, behavior and development outcomes in the index child. Future work regarding the effects of birth spacing should include a focus on the index child.