This paper describes a single case study design examining the experiences of 14 undergraduate psychology students in Spain who participated in a group psychology course with an analytic, experiential group training component. Our goal was to better understand trainees' experiences as participants in the groups and gather their perceptions on the main mechanisms of learning that occur. Qualitative data came from participants' personal reflective journals, and thematic analysis was used to code these data. Quantitative data came from participants' pre-post scores on a therapeutic factors inventory (Yalom's therapeutic factors). Test scores suggest that altruism, universality, cohesion, increased among participants, from pre- to posttest. In addition, qualitative analysis revealed that the group process followed an expected progression (e.g., hesitant and superficial, to deep and emotionally charged interventions, to themes surrounding closure and integration). We review learning mechanisms identified by participants, such as practice in the observer role and the use of silences in the group. Finally, we review the usefulness of an experiential approach in helping undergraduate students learn about group process, develop interpersonal skills, experience personal growth, and acquire group facilitation skills. Study limitations are also discussed.