Maxima was an intervention project that focused on assisting teachers to establish more inquiry-based, gender-inclusive, and culturally relevant learning environments. The authors grounded the project by using sociotransformative constructivism as a theoretical framework to steer the implementation of three guiding concepts for professional development. These guiding concepts are as follows: being responsive and theoretically explicit, providing ongoing and on-site support, and reflexive approaches to collaboration. The analysis of multiple data sets gathered during Year 1 of the project indicates that most of the teachers responded positively to the proposed guiding concepts and significantly changed their teaching practice. (Contains 1 figure and 8 notes.)