Once a child has been identified as an ELL, schools are required to monitor his or her English development through an annual assessment (many states continue to use the WIDA ACCESS for ELLs test for this purpose). Moreover, federal law requires schools to assure that ELLs gain proficiency within a "reasonable" amount of time. Conservative estimates are that it takes between five to seven years to acquire academic English, but many factors, such as age and prior education, influence the amount of time it takes to acquire a second language.

In addition to English proficiency, schools are required to assess ELLs' content knowledge through state standardized tests. ELLs are exempt from one administration of state standardized assessments in Reading and Language Arts until they have completed a full year in a U.S. school, but after that are required to be tested along with their grade-level peers.