Professional learning groups are becoming a popular form of teacher development in mathematics. Due to the personal nature of the groups, as well as differences in initial beliefs and capacity, teachers may respond differently to such opportunities. A total of 14 teachers were observed over a three-year period, and two contrasting participants, each involved for two years, were chosen for in-depth study in order to illustrate a range of responses. The teachers were chosen from the larger sample to exemplify differences in initial capacity as well as varying responses to the group activities. Both teachers, regardless of their differing initial beliefs and knowledge, demonstrated growth over a two year period. Such development however was in relation to their initial beliefs and capacity.