This is the first in a series of briefs the Houston Education Research Consortium (HERC) will release on long-term English learners (LTELs). The full study will examine LTELs in Texas, with particular focus on 10 Houston-area public school districts. Currently, there is no formal definition of LTEL in Texas. The purpose of this brief was to compare three common definitions of LTEL (remaining an English learner for more than three years, more than five years, and more than seven years) using seven criteria based on its research and practitioner application to identify the most useful definition. The definition of LTEL as remaining EL after five years satisfied the most criteria. Using this definition of LTEL, HERC will move forward with this study by examining characteristics of LTELs and the schools that serve them, overall patterns of reclassification for ELs and LTELs, and the educational outcomes of LTELs.