A crucial component of child language acquisition is successful generalization. First, a speaker must acquire abstract knowledge of how a particular linguistic-structure conveys meaning, and use this knowledge to generalize the structure to new lexical-items. For example, a speaker can use abstract knowledge of a SUBJECT-VERB-OBJECT structure to produce a sentence such as The man rolled the ball, even if the verb roll has never been encountered in this structure before. Second, a learner must appropriately restrict 'overgeneralizations' whereby a structure is used with an unsuitable verb (e.g. *The man fell the boy). The most prominent theories regarding restriction of overgeneralizations are based on frequency of use and (semantic, phonological or pragmatic) compatibility between the item and construction. Since developmental evidence for these accounts is mostly limited to the judgment paradigm, which is unsuitable for testing children aged 5 and under, the aim of this thesis was to examine whether these restriction mechanisms are used by children as young as 3 or 4 - whose generalization mechanisms are at an earlier stage of development - and to develop new paradigms for doing so. Study 1 used a production priming paradigm to examine children's (aged 3-4; 5-6) restrictions of verbal un- prefixation (e.g., *unbend). Children's production probability of verbs in un- form (e.g., *unbend) was negatively predicted by the frequency of the target verb in bare form (i.e., bend/s/ed/ing) and by the frequency of synonyms to a verb's un- form (e.g., straighten for *unbend). Additionally, grammaticality judgments from older children (aged 5-6) revealed that preferences for un- forms were positively related to the extent to which the verb's semantics overlapped with a covert, probabilistic semantic "cryptotype" of meanings thought to be shared by verbs that are grammatical in un- form (e.g., tie, pack, twist, screw, cover). Study 2 investigated whether overgeneralization errors in the domain of English past-tense (i.e., when 'regular' inflections are applied to verbs that require 'irregular' inflection; e.g., *sleeped, *throwed) are best attributed to analogy across exemplars, or to a default, "add -ed" rule applied regardless of a verb's memorized associations. Past-tense forms of novel verbs were elicited by showing children (aged 3-4; 5-6; 6-7; 9-10) animations of an animal performing a novel action described with a novel verb (e.g., gezz; chake) and asking what the animal 'did yesterday'. A verb's likelihood of receiving regular inflection (e.g., gezzed, chaked) was positively associated with its phonological similarity to existing regular verbs, consistent with the analogy-based approach. Study 3 investigated the suitability of an online measure of sentence processing, namely Event Related Potentials (ERP), to investigate the role of verb-frequency in restricting transitive overgeneralizations. In line with previous studies, 'P600' and 'LAN' components were evoked in response to overgeneralization errors. However, the magnitudes of these components were not sensitive to a manipulation of verb-frequency (e.g., *The clown laughed the boy vs. *The clown giggled the boy), raising doubt toward the suitability of ERP for examining the relative acceptability of overgeneralization errors. Overall, the research indicates that even young children's generalizations are sensitive to the linguistic input (i.e., statistical regularities and generalized semantic or phonological patterns of use) and are not well explained by a system of abstract rules that act on discrete categories, whether this applies to syntactic categories (e.g., add -ed to any instance of the category "VERB") or discrete verb classes (e.g., a narrow-range rule that acts invariably on any verb that is part of an 'alternating' verb-class).