A study examined the impact of assuming the role of action researcher in one's own classroom as an example of inquiry-oriented, professional staff development. The study was a part of a comprehensive, longitudinal investigation of the impact of certain professional development experiences on K-12 classroom teachers. A review of the literature and interviews and questionnaire results of teachers who had been involved in a classroom based action research project sought to determine: (1) ways that teachers were influenced by reflectively analyzing their own practices in light of research regarding the teaching-learning process; (2) the impact of the teachers' attitudes toward doing research, reading research, and using the results of research; and (3) the suitability of certain data collection techniques for investigating teacher experiences and beliefs regarding the relationship of educational research and their classroom practices. The teachers felt that there have been positive increases in their knowledge and skills in the following areas: (1) effective teaching-learning; (2) research; (3) reflective thinking habits; (4) the need for continuing professional development; and (5) overall effectiveness as teachers. (CB)