Marcus, Pinker, Ullman, Hollander, Rosen & Xu (1992) claim that when the irregular past form of a verb is known, it is immediately known to be the correct form, such that overregularizations only occur as speech errors, not as a genuine grammatical alternative; as a result, they argue, overregularization rates are, when carefully inspected, very low. In the present paper: (1) it is shown that even if overregularizations are a genuine grammatical alternative, overall rates in samples would still be low for most children; (2) careful analysis shows evidence for substantial overregularization periods in three longitudinal subjects ages 2; 5–5; 2 (Abe), 2; 3–5; 2 (Adam) and 2; 3–5; 0 (Sarah); (3) Abe's much higher rates follow from general developments in his past tense acquisition, in ways not consonant with Marcus et al.'s formulations.