With the recognition of positive psychology within China, there is a pressing need for evidence-based positive psychology interventions (PPIs) tailored to the cultural context of Chinese schools. The goals of the present study were to (a) culturally adapt the Well-Being Promotion Program using the ecological validity model and (b) conduct a preliminary evaluation of its effectiveness. Within a randomized controlled trial, we collected data from 107 eighth-grade students randomly assigned to the intervention (n = 55) or control group (n = 52). A mixed methods approach was used, with analysis of covariance to assess program effectiveness, and content analyses of students' short-answer responses collected from the intervention group. Qualitatively, more than half of students reported having positive feelings and an increase in happiness due to the program. Quantitatively, the study found that the intervention was associated with a significant increase in adaptability, a subcategory of psychological suzhi, following the intervention. Gender breakdown revealed that the intervention had a significant positive effect on boys' cognitive quality, but not girls'. Additionally, it marginally impacted girls' self-management and boys' adaptability quality. However, caution is warranted in interpreting the quantitative results due to limitations, such as a small sample size and a relatively low response rate at Time 2. This pilot study contributes to the literature by bridging the gap between evidence-based PPIs developed in Western contexts and their culturally responsive implementation in Chinese schools. Consequently, the results should be considered as initial evidence warranting further examination of effectiveness, yet with significant potential to advance future cultural adaptations of PPIs. (PsycInfo Database Record (c) 2024 APA, all rights reserved).