Purpose: The present study investigated the effects of selected measures of language experience (parent-reported estimates of frequency of output and language use) and language ability (parent-reported language proficiency and mean length of utterance in words) on the segmental accuracy of Spanish- and English-speaking bilingual children. Method: The phonological skills of 50 typically developing bilingual Spanish-English children (mean age = 5;9 [years;months]) were examined. Independent variables included parent estimates of language use, language proficiency, and frequency of language output (5 groups), as well as a direct language measure (mean length of utterance in words) to predict the dependent segmental accuracy measures (percentage of consonants and vowels correct). Results: Frequency of language output did not have an effect on any of the English or Spanish segmental accuracy measures. However, parent-reported language use and language proficiency as well as the direct measure of language ability (mean length of utterance in words) had various effects on segmental accuracy. Those effects differed, however, in language-specific patterns. Conclusions: Parental estimates of language use and language proficiency are useful for predicting the phonological skills of bilingual Spanish- and English-speaking children, and augmenting them with a direct measure of language ability as a predictor of segmental accuracy is desirable. (Contains 10 tables.)