Research shows correlations between proficiency and language attitudes. Other studies associate performance in young bilinguals more strongly with adult language input and practice at home than with individual attitudes in youth. No studies, however, have examined how attitudes and family practice are implicated in the linguistic development of bilingual children. This study examines (1) the interplay between attitudinal and objective factors in setting the input conditions relevant for child bilingual acquisition; (2) how parental attitudes and community context shape home language practices and input conditions; and (3) how input conditions determine bilingual proficiency and degree of morphosyntactic transfer in young bilinguals. Twenty three bilingual children participated in the study. Children completed an elicited narrative and a word order task to assess the extent of transfer. They were asked to repeat sentences with clitics in reconstruction environments. If object pronoun linearization was vulnerable to transfer, children with stronger English dominance were expected to favor postverbal positioning. Results show strong correlation between family’s attitudes to Spanish and bilingualism, but only moderate association between these and language practice. The most important difference in terms of dominance between the children related to onset of bilingualism. Results from the repetition task show a tendency by bilinguals to reposition preverbal pronouns as postverbal, a pattern not attested among monolinguals, and a lesser degree of the preverbal pattern. The simultaneous bilinguals favor the predicted transfer pattern more strongly, and also show high rates of pronoun omissions. These results suggest that input conditions are the primary factor in language maintenance in young bilinguals.