Individual and focus group interviews were conducted to identify school-related factors that influence the process and quality of implementation of the Tier 1 Program of the Project P.A.T.H.S. in Hong Kong. Results of this case study approach showed that the program implementation quality was generally high. Factors that facilitate the implementation of the program were identified, including administrative support from the school and social work agency, presence of dedicated teachers, positive perceptions of the program among teachers, the teachers' self-disclosure, effective continuous assessment, and excellent co-teaching mode. Difficulties encountered by the school in the process of implementation were also observed. Based on the present findings, school-related process variables that facilitate or impede the implementation of positive youth development programs in the Chinese context are discussed.