In the context of increasing legislative emphasis on universal screening for reading problems, the accurate and equitable assessment of English learners (ELs) remains a pressing concern. This study examines how kindergarten and first-grade students' performance on early literacy measures in English is affected by their English proficiency. In this paper, we report on performance on measures of deletion, picture naming, sentence repetition, letter naming fluency, word and nonword reading, and rapid object naming across the school year. Drawing on a diverse and representative sample of 3,064 students across 31 U.S. Californian schools, we addressed two main research questions. First, we compared the performance of English-only students (EO) to ELs and to students identified as English-proficient (EP) but speaking another language at home. Findings indicated that ELs consistently scored lower than their EO and EP peers across all assessments. Second, we compared growth patterns. While most measures showed similar growth rates, a significant performance gap remained for ELs (p < 0.001). Notably, EP students displayed distinct performance patterns, outperforming EO students in most tasks, except for those demanding more vocabulary. Our findings emphasize the importance of tailored assessment approaches and consideration of English proficiency when interpreting ELs' performance.