Purpose: This study evaluated the impact of 1-day workshops on teachers' knowledge, practices, and dispositions using known characteristics of quality professional development and Guskey's five levels of professional development evaluation. Method: Eight workshops were evaluated over a 2-year period using pre/post surveys, end-of-workshop surveys, observations, interviews, and artifacts. Results: Participants reported high levels of satisfaction and trainer effectiveness scores at the end of workshops. Statistical analyses revealed improvements in four of six outcome variables 4 weeks after workshop completion: self-reported knowledge, utilization of implementation strategies, presence of a community of continued learning, and teacher efficacy. Qualitative data corroborated these results but offered mixed evidence of teacher implementation and improved student outcomes. Discussion/Conclusion: Findings confirm that 1-day workshops aligned with characteristics of quality professional development are highly valued by participants and can improve teachers' knowledge and efficacy, but teacher practice and student learning may be more difficult to influence and document.