BACKGROUND: The theory of planned behavior (TPB) has been used to explain breastfeeding behaviors in Western cultures. Theoretically-based investigations in other groups are sparse. OBJECTIVE: To evaluate cross-cultural application of TPB-based models for breastfeeding duration among new mothers in Hong Kong. METHOD: First-time breastfeeding mothers (N = 209) with healthy newborns provided self-reports of TPB predictor variables during postpartum hospitalization and information about breastfeeding experiences at 1, 3, 6, 9, and 12 months postdelivery or until they weaned. Three predictive models were proposed: (a) a strict interpretation of the TPB with two added proximal predictors of breastfeeding duration; (b) a replication with modification of the TPB-based model for more fully employed breastfeeding mothers from a previous study (Duckett et al., 1998); and (c) a model that posited perceived control (PC) as a mediating factor linking TPB motivational variables for breastfeeding with breastfeeding intentions and behavior. LISREL was used for the structural equation modeling analyses. RESULTS: Explained variance in PC and duration was high in all models. Overall fit of the strict TPB model was poor (GOFI = 0.85). The TPB for breastfeeding employed women and the PC-mediated models fit equally well (GOFI = 0.94; 0.95) and residuals were small (RMSR = 0.07). All hypothesized paths in the PC-mediated model were significant (p <.05); explained variance was 0.40 for perceived control and 0.36 for breastfeeding duration. DISCUSSION: Models were interpreted in light of the TPB, previous findings, the social context for breastfeeding in Hong Kong, and statistical model-building. Cross-cultural measurement issues and the need for prospective designs are continuing challenges in breastfeeding research.