Using student-level longitudinal data from one large urban school district, I examine Long-term English Learners' (LTELs) characteristics and their linguistic and academic performance in comparison to on-track English learners and initially fluent students. I also investigate what factors are related to their becoming LTELs. This study focuses on English learners (ELs) whose home language is Spanish, the major language group in the district. The findings indicate LTELs often have disadvantaged characteristics and underperform against non-LTELs across grades, and ELs with disabilities are more likely to become LTELs than other ELs. Not all ELs with the highest initially English proficiency avoided becoming LTELs, which provides implications on the EL classification and programs.