This study aimed to: (1) investigate the knowledge and competencies in classroom action research among pre-service teachers in the 12+2 Primary Teacher Education Program at Savannakhet Teacher Training College; and (2) evaluate the effectiveness of a coaching intervention on their research outcomes. The sample comprised three pre-service teachers undertaking their practicum during the second semester of the 2025-2026 academic year. The research instruments included nine classroom action research coaching plans-developed based on Haas's coaching framework-as well as a knowledge test, a competency assessment rubric, and a research report evaluation form. Quantitative data were analyzed using mean and standard deviation, while qualitative data were examined through content analysis. The findings revealed that: (1) pre-service teachers' knowledge of classroom action research significantly improved following the coaching intervention ($p<.05$), with overall research competencies reaching a high level. (2) The overall quality of the action research reports was assessed as moderate. The study concludes that while coaching effectively enhances cognitive processes and practical skills, the professional practicum center should implement supplementary training to address procedural gaps such as literature review and academic citation resulting from time constraints. It is recommended that future interventions provide more intensive practical training to improve research quality.