Between the ages of 3 and 7 years, children have been observed to produce verb argument structure overgeneralization errors (e.g., Don't giggle me; Bowerman, 1982, 1988; Pinker, 1989). A number of recent studies have begun to find evidence that the precise distributional properties of the input may provide an important part of the explanation for why children retreat from overgeneralization errors (Brooks & Tomasello, 1999; Brooks, Tomasello, Dodson, & Lewis, 1999). The current study evaluates the role of entrenchment (Braine & Brooks, 1995) in constraining argument structure overgeneralization errors using a grammaticality judgment task. The 5-year-olds, 8-year-olds, and adults were presented with examples of argument structure errors containing high and low frequency verbs matched for semantic class and asked to indicate whether, or the extent to which they found the sentences to be grammatical. The data show that across all groups, sentences with argument structure errors containing low frequency verbs were judged to be significantly more grammatical than those containing high frequency verbs. These findings provide further support for the entrenchment hypothesis and suggest that verb frequency plays an important and continuing role in determining a speaker's choice of verb argument structure.