This dissertation explored how individual characteristics of members, communication patterns, relative power, and collective sensemaking about the concept of Teaching-as-Research in a community of practice influenced any changes in members? professional identities. Teaching-as-Research involves using methods similar to those used in research (hypothesizing, implementing, analyzing, and modifying) to develop and apply teaching strategies. The case study involved thirteen instructors of undergraduates in a science department at a research university participating in an academic community of practice. Weick?s theory of sensemaking (1993, 1995) provides the theoretical foundation for this study. Major concepts in the conceptual framework include individual characteristics, professional identity, community of practice, and sensemaking, both individual and collective. The study proposes relationships among these concepts, and explores how, over time, they interact to effect changes in the professional identities of individual instructors.