This study aimed to investigate the influence of gender on the satisfaction of Vietnamese K-12 teachers who participated in Teaching Activity Groups (TAGs), a collaborative professional development (PD) initiative. Using a quantitative approach, questionnaire data was collected from a purposive sample of 147 teachers (108 females, 39 males). The data were subjected to descriptive statistical analysis and Independent Sample t-tests to discern potential gender-based differences in teachers’ satisfaction with TAGs and their perceived impact on teachers’ PD. The results revealed nuanced disparities in satisfaction levels between female and male participants, with generally higher satisfaction levels exhibited by females. Notable areas of difference included knowledge acquisition, skills acquisition, school support, and issue resolution. These areas were indeed discussed in the content, providing a detailed analysis of where gender differences in satisfaction were most pronounced. The results underscore the relevance of gender considerations in PD studies and offer insights for policy and practice in the Vietnamese educational landscape. The study concludes by highlighting the need for further research to explore these gender dynamics and their underlying causes in greater depth.