This study explored science and mathematics teachers' knowledge and beliefs about project-based instruction (PBL). Data included two focus groups, and a 12-item questionnaire administered to 138 teachers. The response rate was 70% (n=96). Results show strong teacher knowledge of PBL Gold Standard Design Elements/Teaching Practices, but low usage by teachers (68%) as less than 26% of instructional time was used to implement PBL. Of the respondents, 33 indicated they used PBL as a teaching strategy. Teachers felt prepared to use PBL, suggested it made learning fun, and helped students acquire academic content and 21st century skills. Challenges included: funding support, accountability requirements, time constraints, and lack of professional development support.