Education policy analysts and professional educators have called for more and better professional learning opportunities for in-service teachers, and for at least 30 years economists called for more content training for high school economics teachers. Using new data from all Georgia high school economics students, we assess the impact of in-service teacher workshops on the performance of students on a high-stakes end-of-course economics exam. Controlling for student characteristics and teacher fixed effects, we find a positive and significant impact of teacher workshop attendance--once teachers have attended three workshops--on student test scores. Furthermore, the results suggest that in-service workshops for economics teachers offer a cost-effective way to provide content training. (Contains 1 figure, 1 table and 7 notes.)