Purpose: Sentence repetition is a measure that has been commonly used to assist in the identification of language disorders for bilingual individuals. It has been observed that bilinguals with typical and atypical language skills produce different error patterns when repeating sentences. Those with typical language most commonly replace target words, and those with language disorders most commonly omit words and nominal or grammatical morphemes during repetition. However, the underlying factors associated with different error types are inadequately understood. The present paper evaluated individual-level factors, like cognitive-linguistic skills, and stimuli-related factors, like lexical-semantic content, to see how each predicted omission and substitution errors during sentence repetition for bilingual and monolingual adults. Method: Twenty-one Spanish-English speaking adults and twenty monolingual English-speaking adults completed four cognitive-linguistic tasks. The models predicted substitution or omission errors during a sentence repetition task containing low semantic predictability sentences that varied in concreteness and frequency. The independent variables were scores derived from the LexTALE vocabulary test, which represented lexical knowledge in English; forward and backward digit span tasks, which together represented verbal memory; and a language history questionnaire, used to estimate exposure to English. Research Question 1 evaluated how language background (i.e., monolingual or bilingual) and lexical knowledge were associated with omission and substitution errors during sentence repetition. Research Question 2 evaluated how concreteness, frequency, syntactic structure, and part of speech interacted with cognitive-linguistic factors to predict errors for bilingual and monolingual adults. Research Question 3 used the data derived from bilingual performance on the sentence repetition task to evaluate how lexical knowledge predicted the semantic similarity between substitution errors and the target words they replaced. Results: The results showed that bilingual and monolingual adults exhibited different patterns of error production during sentence repetition. Bilingual adults were more likely to produce substitution errors than monolinguals after accounting for lexical knowledge and verbal memory abilities. However, both groups were equally likely to omit words during sentence repetition. The evaluation of how individual-level and sentence-related factors interacted to predict omission errors identified additional differences for bilingual and monolingual adults that were associated with language experience. For bilinguals, omission errors were negatively associated with exposure to English with this association being modulated by lexical knowledge. Moreover, bilinguals with lower amounts of English exposure were more likely to omit concrete or low frequency words, with both effects being modulated by lexical knowledge. Substitution errors were associated with verbal memory and word-related factors, but not with lexical knowledge or English exposure. For monolinguals, verbal memory variable was associated with omission errors, but lexical knowledge was not significant in any model. An exploratory analysis was conducted to see if differences in the semantic similarity between target words and substitution errors could be analyzed to derive information about bilingual individuals' lexical knowledge. The results indicated that those relatively high amounts of exposure to English were more likely to replace low frequency target words with ones that were conceptually similar in meaning compared to those with less exposure to English. Bilingual adults with relatively low exposure to English replaced low frequency targets with unrelated words, with this association being modulated by lexical knowledge. It is possible that the association between lexical knowledge and the semantic similarity of substitution errors could, in part, account for the lack of association between lexical knowledge and overall substitution error rates in the other models. Conclusion: Improving the understanding of which cognitive-linguistic factors underlie error productions during sentence repetition would aid in the accurate interpretation of task performance for linguistically diverse populations. In clinical practice errors are treated equally by most scoring protocols. The present paper identified a potential weakness in this approach by documenting that Spanish-English bilinguals produce qualitatively different substitution errors depending upon their English exposure and lexical knowledge. Therefore, important information about individual differences in language skills might be missed by traditional scoring protocols.