While adoption of competency-based medical education for clinical training is well documented, it is less common in preclinical medical education. The gross anatomy laboratory is an opportune venue to implement competency assessment during preclinical training. This mixed-methods study determined how first-year medical student assessments of communication skills in the gross anatomy lab change over time and analyzed student reflections to contextualize the experiences they had developing the Communication competency. First-year medical students at the University of Louisville completed self- and peer-assessments using the Communication Assessment Tool (CAT) at the beginning and end of their gross anatomy course (n = 83). The students also completed three competency development portfolio (CDP) entries throughout the course (n = 83). Qualitative thematic analysis with grounded theory was used to analyze comments related to communication in the CDP reflections during the course. There was a significant increase in CAT-peer-assessment scores from Time 1 (M = 4.70, SD = 0.331) to Time 2 (M = 4.87, SD = 0.264), p < 0.001. There was also a significant increase in CAT-self-assessment scores from Time 1 (M = 4.50, SD = 0.472) to Time 2 (M = 4.77, SD = 0.386), p < 0.001. Thematic analysis of CDPs revealed that students developed skills in imparting information, gathering information, and team communication skills throughout the gross anatomy course. First-year medical students reflected upon and demonstrated self- and peer-perceived growth in the Communication competency in the gross anatomy lab context.