We present morphological analyses of verb inflections produced by 15 Spanish-speaking children (age range: 1;7 to 4;7) taken from longitudinal and cross-sectional samples of spontaneous speech and narratives. Our main observation is the existence of a dissociation between regular and irregular processes in the distribution of errors: regular suffixes and unmarked (non-alternating) stems are over-extended to irregulars in childrenʼs inflection errors, but not vice versa. We also found that overregularization errors at all ages are only a small minority of the childrenʼs irregular verbs, that the period of overregularization is preceded by a stage without errors, and that the onset of overregularizations is connected to the emergence of obligatory finiteness markings. These findings are explained in terms of the dual-mechanism model of inflection.