The Philippines is characterized by sustained economic growth and political stability, yet sexual and reproductive health indicators have stalled or even worsened in recent decades. We employed an innovative, mixed-methods approach-Systematic Anomalous Case Analysis-to gain insights into these worsening trends by examining sexual and reproductive decision-making among a cohort of young adults in Metro Cebu, Philippines. We first analyzed longitudinal data (1998-2009) to predict reproductive outcomes (i.e., age of first sex, number of living children) among participants in the Cebu Longitudinal Health and Nutrition Survey to identify cases (predicted and anomalous) with whom we subsequently conducted qualitative, in-depth interviews in 2013-14 (n = 48). Analysis of the qualitative data revealed unique social and contextual factors that shaped patterns of sexual and contraceptive decision-making across three, distinct reproductive life stages: (1) at first sex, (2) after the birth of first child, and (3) after the birth of several children. However, gendered roles and expectations exerted strong influences on sexual and reproductive outcomes across these life stages. Finally, we identified two constructs from our qualitative analysis-sexual fluidity and sexual agency-that deserve further examination and integration into theoretical and empirical models of sexual and reproductive decision-making. © 2020 The Population Council, Inc.