Objective: Hand washing and sleep hygiene are two important health behaviors. The purpose of the current study was to identify the motivational and volitional antecedents of college students' hand washing and sleep hygiene behaviors based on an integrated model of behavior that combined social-cognition constructs from the Theory of Planned Behavior (TPB) and Health Action Process Approach (HAPA). Methods: Using a prospective design, college students (N = 1106) completed a survey assessing the motivational constructs of action self-efficacy, attitudes, subjective norm, perceived behavioral control, intentions, and behaviors of hand washing and sleep hygiene at Time 1. Demographic variables were also collected. One month later, at Time 2, college students (N = 524) self-reported on their volitional factors of maintenance self-efficacy, action planning, coping planning, and behaviors of hand washing and sleep hygiene. A further 2 months later, at Time 3, college students (N = 297) were asked to self-report on their hand washing and sleep hygiene behaviors over the past month. Findings: Data were analyzed using variance-based structural equation modelling. Results showed significant direct effects of attitudes, subjective norm, and perceived behavioral control on intentions; significant direct effects of action self-efficacy on maintenance self-efficacy; and significant direct effects of maintenance self-efficacy on action planning and coping planning. Significant direct effects of intention on action planning (sleep hygiene only), and significant direct effects of intention, maintenance self-efficacy (hand washing only), action and coping planning on behavior were also observed. Action planning also moderated the intention-behavior relationship, but only for hand washing. There were also significant total indirect effects of action self-efficacy on behavior mediated by maintenance self-efficacy, action planning, and coping planning for both behaviors, and significant total indirect effects of subjective norm and perceived behavioral control on behavior mediated by intention for sleep hygiene. When past behavior was included in the integrated model predicting all the psychological variables and behavior, all of the structural relations were attenuated. Discussion: Current findings indicate that college students' hand washing and sleep hygiene behaviors are a function of both motivational and volitional factors. Findings also indicate that the TPB and HAPA pathways might differ for the two health behaviors. Implications of the current findings for future health interventions aimed at improving college students' hand washing and sleep hygiene are discussed.