Research regarding typical English language development in children who are bilingual is of interest for speech-language pathologists, but often this information is not available to them. As a result, many individuals ﬁnd themselves believing false stereotypes about children who are bilingual, such as the idea that bilingualism causes developmental delay or disorders. For example, individuals do not realize the differences in past tense development for bilingual children versus monolingual children, a form that is often diﬃcult for monolingual English-speaking children with developmental language delays. By focusing on a speciﬁc aspect of language development, such as English past tense acquisition of children who are bilingual, and observing changes in MLU and grammaticality that accompany acquisition, this study seeks to increase the existing knowledge on bilingualism and language development. Speciﬁcally, we will answer the following questions: a) At which grade level do Spanish-English bilingual children master English past tense after they enter English-only schooling in preschool? b) What types of errors do the children make with regular past tense? c) what types of errors do they make with irregular past tense? and d) What is the level of English grammaticality and MLUw at each grade level in English after children enter preschool? This study examined past-tense accuracy, MLU, and grammaticality development over a period of 5 years, in 13 children who were participants in a larger project called the Language and Reading Research Consortium (LARRC). Children were followed from preschool to third grade. They provided a yearly language sample by retelling one of the wordless Marianna Meyer and Mercer Meyer frog books, such as Frog on His Own or A Boy a Dog a Frog and a Friend. The language samples were then transcribed, coded, and analyzed using the Systematic Analysis of Language Transcripts (SALT) software. Results indicate that children progressively improved over the years, with children reaching over 80% accuracy with past tense by year 3 or first grade; they demonstrated the most improvement in MLU between years 2 to 3 and years 3 to 4; and they showed a gradual improvement in grammaticality each year, with the exception of no increase between years 4 to 5. Findings from the study indicate that there is leveling in all three areas after 2nd grade. These results contribute to our understanding of normal English language development in bilingual children and may improve assessment when we evaluate their performance in English as a second language.