Policy Points: Historically, reforms that have increased the duration of job-protected paid parental leave have improved women’s economic outcomes. By targeting the period around childbirth, access to paid parental leave also appears to reduce rates of infant mortality, with breastfeeding representing one potential mechanism. The provision of more generous paid leave entitlements in countries that offer unpaid or short durations of paid leave could help families strike a balance between the competing demands of earning income and attending to personal and family well-being. CONTEXT: Policies legislating paid leave from work for new parents, and to attend to individual and family illness, are common across Organisation for Economic Co-operation and Development (OECD) countries. However, there exists no comprehensive review of their potential impacts on economic, social, and health outcomes. METHODS: We conducted a systematic review of the peer-reviewed literature on paid leave and socioeconomic and health outcomes. We reviewed 5,538 abstracts and selected 85 published papers on the impact of parental leave policies, 22 papers on the impact of medical leave policies, and 2 papers that evaluated both types of policies. We synthesized the main findings through a narrative description; a meta-analysis was precluded by heterogeneity in policy attributes, policy changes, outcomes, and study designs. FINDINGS: We were able to draw several conclusions about the impact of parental leave policies. First, extensions in the duration of paid parental leave to between 6 and 12 months were accompanied by attendant increases in leave-taking and longer durations of leave. Second, there was little evidence that extending the duration of paid leave had negative employment or economic consequences. Third, unpaid leave does not appear to confer the same benefits as paid leave. Fourth, from a population health perspective, increases in paid parental leave were consistently associated with better infant and child health, particularly in terms of lower mortality rates. Fifth, paid paternal leave policies of adequate length and generosity have induced fathers to take additional time off from work following the birth of a child. How medical leave policies for personal or family illness influence health has not been widely studied. CONCLUSIONS: There is substantial quasi-experimental evidence to support expansions in the duration of job-protected paid parental leave as an instrument for supporting women’s labor force participation, safeguarding women’s incomes and earnings, and improving child survival. This has implications, in particular, for countries that offer shorter durations of job-protected paid leave or lack a national paid leave entitlement altogether.