The songs of the Eastern tufted titmouse (Parus B. bicolor) and the black-crested titmouse (Parus B. sennetti) were examined as a possible systematic tool. From nine sites, 65 song types were identified, falling into four categories: one-note phrase, two-note long-short phrase, two-note short-long phrase, and three-note phrase songs. Canonical discriminant analysis on morphometric parameters revealed greater variation in song between sites than within sites. Black-crested titmice typically sing at higher dominant frequencies, shorter phrase durations, a higher number of phrases per song, and a smaller repertoire than tufted titmice. Black-crested repertoires were composed mostly of one-note phrase songs and a few two-note phrase songs. Tufted titmice repertoires had approximately equal proportions of one-note and two-note phrase songs with one three-note phrase song at each site. Differences in body size and habitat density may explain the higher dominant frequencies found at black-crested sites. The possible occurrence of dialects and the role of learning may account for all differences in song. However, their impacts on titmice songs must be determined before song can be used as a reliable systematic tool for the tufted titmouse complex.