This study examines the trends of elementary and middle school teachers’ participation in content-focused professional development (PD) in Korea using teacher samples from the first and second cycles of The Study on the Actual Status and Quality in School Education. Using chi-square tests and t-tests, we found 1) both elementary and middle school teachers tended to participate in content-focused PD more actively than non-content-focused PD; 2) middle school teachers had a decreasing pattern of participation in content-focused PD; 3) elementary school teachers showed mixed results in participation in content-focused PD; and 4) elementary school teachers tended to participate in content-focused PD more actively than middle school teachers. More support for both middle and elementary school teachers is needed to encourage participation in content-focused PD more actively.