Previous work has shown that masked-sentence recognition is particularly poor when the masker is composed of two competing talkers, a finding that is attributed to informational masking. Informational masking tends to be largest when the target and masker talkers are perceptually similar. Reductions in masking have been observed for a wide range of target and masker differences, including language: Performance is better when the target and masker talkers speak in different languages, compared with the same language. The present study evaluated normal-hearing adults' sentence recognition in a two-talker masker as a function of the perceptual similarity between the target and each of the two masker streams. The target was English, and the maskers were composed of English, time-reversed English, or Dutch. These three masker types are known to vary in the informational masking they exert. The two talkers within the two-talker maskers were either congruent (e.g., both English) or incongruent (e.g., one English, one Dutch). As predicted, mean performance was worse for the congruent English masker than the congruent time-reversed English or congruent Dutch maskers. Incongruent two-talker maskers, with just one English masker stream, were only modestly less effective than the congruent English masker. This result indicates that two-talker masker effectiveness was determined predominantly by the one masker stream that was most perceptually similar to the target. Speech recognition in a single-talker masker differed only marginally between the English, Dutch, and time-reversed English masker types, suggesting that perceptual similarity may be more critical in a two-talker than a one-talker masker.