Two studies investigated 3- to 5-year-olds' trust in a reliable informant when judging novel labels and novel plural and past tense forms. In Study 1, children (N = 24) endorsed the names of new objects given by an informant who had earlier labeled familiar objects correctly over the names given by an informant who had labeled the same objects incorrectly. In Study 2, children (N = 24) endorsed novel names given by an informant who had earlier expressed the plural of familiar nouns correctly over one who had expressed the plural incorrectly. But children overwhelmingly endorsed the regular plural and past tense forms of new words provided by the formerly unreliable labeler (Study 1) or morphologist (Study 2) rather than irregular forms of those words provided by the formerly reliable informant.