The challenge facing children learning language bilingually has led to efforts to improve the assessment and treatment of language learning difficulties. One of these efforts is the development and validation of the Spanish-English Language Proficiency Scale (SELPS). Previous research has been performed to validate the scale for English language proficiency but not for Spanish language proficiency. Twenty-four sequential bilingual children produced spontaneous narrative language samples that were rated using the SELPS and coded for language sample variables using the Systemic Analysis of Language Transcripts software. Several language sample variables, most notably the Subordination Index, the number of omitted bound morphemes, and the number of code-switched words, were correlated with the SELPS subscale scores and total score. Findings have implications for screening the Spanish language proficiency of Spanish-English bilingual children who are between four and eight years of age.