**Aims** We developed the Teaching Mindset Practices (TMP) observation protocol to capture implementation quality of Brainology, a growth mindset intervention. The core of the TMP is a set of teaching practices that we hypothesized would promote improvements in students’ proximal outcomes after participating in Brainology—e.g., their growth mindset, and learning goals. Data collected through the TMP were used to (1) support teachers implementing Brainology and are being used to (2) understand the conditions that make Brainology more or less successful. **Indicators of Implementation Quality** Following Humphrey and colleagues (2017), we conceived of the implementation of Brainology as a multi-faceted process. Therefore, we assessed multiple aspects of implementation: - Adherence, or the degree to which teachers followed Brainology lesson plans - Quality of delivery, or the teaching practices that promoted students’ proximal outcomes after participating in Brainology - Student engagement, or the extent to which most students participated (e.g., asked questions, listened to instructions) during Brainology lessons - Contamination, or the extent to which teachers in the control group used teaching practices such as growth-minded messages and process feedback. **Data Collection** **Brainology Group**. Teachers were observed before, during, and after implementing Brainology. Trained observers visited teachers multiple times during the delivery of 20 Brainology lessons. During each visit, observers took notes on implementation quality. After observing each session, they then rated teaching practices and student engagement based on their notes. **Control Group**. Teachers were observed teaching science, math, or English Language Arts in the same months that Brainology teachers were observed, but with less frequency. During each visit, observers took notes on the same teaching practices & student engagement factors observed in the Brainology group. Observations provided a measure of potential contamination—e.g., high rates of growth-minded messages or activities that resembled Brainology lessons. After observing each session, they then rated teaching practices and student engagement based on their notes. Across treatment groups, approximately half of the classroom observations were conducted by more than one observer, which resulted in a wide range of data points across teachers (Range = 3 – 42).