The burdens related to mental illness have been increasingly recognized in many countries. Nevertheless, research in positive mental health behaviors remains scarce. This study utilizes the Predisposing, Reinforcing, and Enabling Causes in Education Diagnosis and Evaluation (PRECEDE) model to identify factors associated with mental health promoting behaviors and to examine the effects of these behaviors on mental well-being and quality of life among 941 adults in Hong Kong. Structural equation modeling shows that sense of coherence (predisposing factor), social support (reinforcing factor), and daily hassles (enabling factor) are significantly related to mental health promoting behaviors, which are associated with mental well-being and quality of life. Results of bootstrap analyses confirm the mediating role of mental health promoting behaviors on well-being and quality of life. The study supports the application of the PRECEDE model in understanding mental health promoting behaviors and demonstrates its relationships with well-being and quality of life.