This study examined the association between paternal multiple partner fertility (MPF; having children with two or more partners) and indicators of environmental chaos (partnership instability, residential instability, work stability, material hardship, and perceived social support) among unmarried, nonresident fathers. Survey data from the Fragile Families and Child Wellbeing Study (N = 873) were used to compare unmarried nonresident fathers who experienced MPF to those who had children with one partner. Results show that paternal MPF is associated with most indicators of environmental chaos (greater partnership instability, residential instability, work instability, material hardship) but not social support. Results suggest that fathers who experience MPF face challenges beyond those of other nonresident fathers. Policies and interventions should address aspects of instability and hardship that are unique to paternal MPF in order to encourage fathers' positive contributions to children and families. Directions for future research are discussed.