This paper describes two professional development institutes in project-based science. We collected data from these institutes in the form of structured questionnaires, individual written reflections by the teachers, and focus-group interviews. An analysis of the data revealed three factors that had been underrepresented in previous research: comfort, technology, and balance. In terms of comfort, the teachers expressed a need for both physical and psychological comfort for them to learn. The technological emphasis in our institutes caused teachers to stress in their comments our developing software. We found that, depending on teachers' previous knowledge, technology could be a barrier or a support to the success of institutes. Finally, we found a necessity to balance elements within the institute and a need to balance cognitively demanding time on task with less demanding opportunities for informal interaction.