This exploratory study investigated the experiences of teachers who participated in a collaborative inquiry project. This was designed to gain insights into the learning dispositions (skill, inclination and sensitivity) participants reported when undertaking this form of professional learning. The specific inquiry initiative utilised Design-based Research (DBR). Data for this mixed-method study were generated from 109 teachers in an urban school district in California. The findings indicate that some important differences exist between the way individual teachers think and act when undertaking collaborative teacher inquiry. This enabled the development of a typology of four teacher dispositions and an understanding of how we might cultivate these to enhance the impact of inquiry-based professional learning.