The purpose of this study was to examine the relationship between preservice music teachers' primary instrument background and their teaching effectiveness in brass and woodwind techniques classes. Study participants (N = 135) were preservice music teachers enrolled in secondary instrument techniques courses (brass and woodwinds) from fall 2011 through spring 2015 in three universities. Participants taught a 10-minute video recorded lesson to a beginning-level university student on a brass or woodwind instrument at the end of the semester. All videos were subsequently assessed by two researchers using a researcher-designed rubric. The results of analyses of variance showed that brass-teaching scores tended to be higher than woodwind-teaching scores for all groups. Brass players taught brass more effectively than woodwind players, and woodwind players taught woodwinds better than brass players. Brass and woodwind players scored higher than percussionists, vocalists, pianists, and string players in both brass and woodwind teaching. Implications for music teacher education are discussed.