This paper describes a study of the development of professional identity among employees in small and medium sized enterprises (SMEs) participating in large-scale company-wide training programs. Managers and employees in 175 SMEs in Finland participated. These two research questions were posed: (1) are there differences in the perceptions of professional identity between age groups, men and women, managers and other employee groups, staff with different educational backgrounds, and staff from different industries/businesses; and (2) what is the development of perceived professional identity measured before and after the training? Professional identity was measured using a 30-item self-report questionnaire. Attrition during the program was described as a significant problem. Data were gathered at the beginning of the training program and a follow-up was completed at the end of the program (five years). Among the findings were the following: (1) weaker professional growth motivation was associated with older age groups, blue-collar workers, and lower educational levels; (2) professional competence was highest among older workers and workers with more education; (3) younger age groups have greater professional growth motivation; and (4) women experience less professional frustration than men and were more committed to their work. The training program decreased professional frustration and increased perceived professional competence significantly. (Contains 33 references.) (SLR)