This report outlines a 2-year investigation into how secondary science teachers used professional development (PD) to build scientific classroom discourse communities (SCDCs). Observation data, teacher, student, and school demographic information were used to build a hierarchical linear model. The length of time that teachers received PD was the exclusive predictor of change over time, whereas a schools' percentage of low socioeconomic students predicted how PD concepts was initially implemented. Prior to PD teachers expressed a desire to increase opportunities for students to engage in SCDCs, but found some aspects more challenging than others to implement. Generally, there were three categories of the teachers' frequency of use of SCDC strategies: (a) "most observed" that required teachers to change their own communication, classroom management, and direct instruction; (b) "occasionally observed" that provided opportunities for greater oral and written discourse to facilitate students' meaning making of science; and (c) "least observed" that encouraged students' executive control of their learning and teachers' use of formative assessment in response to students' diverse learning needs. Teachers identified administrative support, PD strategies, and teacher collaboration as supports for implementation. However, they rated students' science knowledge, diverse language skills, and discourse abilities as the greatest barriers to implementing a SCDC.