Service-learning has gained increasing attention in higher education for its potential to connect academic knowledge with students’ social experiences. In existing studies, reflection is widely recognized as a core component of service-learning; however, it is often approached primarily as a pedagogical technique that supports learning. This article aims to clarify the epistemological nature of reflection and to conceptualize it as a process of constructing theoretical knowledge in the teaching of Scientific Socialism. The study employs a systematic literature review combined with theoretical analysis of key works on service-learning and experiential education. The findings suggest that reflection can be understood as a dialectical cognitive process through which learners, drawing on community service experiences, progressively abstract the essential characteristics and lawful relations of social phenomena, thereby forming theoretical knowledge. This approach contributes to strengthening the theoretical foundation of service-learning and provides a scholarly basis for organizing the teaching of Scientific Socialism in ways that closely link theory with social practice in Vietnamese higher education.