Teachers learn about technology integration through formal, informal, and independent modes, forming their systems of practice for professional learning. Within the context of a technology leadership intervention study, we used multiple linear regressions to investigate relationships between teachers' frequency of participation in each learning mode and their perception of its impact. We found that teachers' participation in each mode significantly predicts their participation in the others, with the strongest relationships being those predicting informal and independent participation. We also found a significant positive relationship between teachers' frequency of participation in and perceived impact of informal and independent learning but no relationship for formal learning. These results support an interrelated teacher system of practice for learning, driven by teachers and leaders.