Purpose:The purpose of this analysis was to understand how grammatical morpheme production in Spanish for typically developing Spanish-English bilingual children relates to mean length of utterance in words (MLUw) and the extent to which different bilingual profiles influence order of grammatical morpheme acquisition. Method:Participants included 228 Spanish-English bilingual children ages 4;0-7;6 (years;months). Grammatical morpheme accuracy was evaluated using an experimental version of the Bilingual English-Spanish Assessment (Peña, Gutiérrez-Clellen, Iglesias, Goldstein, & Bedore, 2014). MLUw data were calculated from children's narrative samples. Production accuracy of plural nouns, singular and plural definite articles, preterite tense, imperfect aspect, direct object clitics, prepositions, subjunctive, and conjunctions was calculated and analyzed as a function of MLUw in Spanish. Level of accuracy on these forms was compared for Spanish-dominant and English-dominant groups. Results:Accuracy was significantly associated with MLUw. The relative difficulty of Spanish grammatical morphemes is highly similar across different bilingual profiles. Conclusions:There are common elements of Spanish that are easy (imperfect, plural nouns, singular articles, conjunctions), medium (plural articles, preterite), or hard (prepositions, direct object clitics, subjunctive), regardless of whether a child is a Spanish-dominant or English-dominant bilingual.