The first step in determining a student's need for language services is through a home language survey. This simple screen asks parents what languages their child speaks. It is typically available to families in English and other major languages (such as DC Public Schools' form). If a parent marks that their child speaks a language other than—or even in addition to—English at home, the child will have his or her English assessed.

After identifying a student as an ELL through the home language survey, some states (such as New York) use an oral interview as an initial assessment of a child's language abilities. Other states conduct a review of a child's school transcripts to see what coursework they have completed in English. The majority of states assess ELLs' English proficiency through a test. For example, thirty-four states use the "WIDA Assessing Comprehension and Communication in English State-to-State for English Language Learners" assessment, better known as the WIDA ACCESS for ELLs. This is a kindergarten through 12th grade test that evaluates a child's reading, writing, speaking, and listening abilities in English across major content areas. The test yields a WIDA proficiency level (one to six), which schools can use to plan for time and intensity of English instruction (within the bounds of state and federal laws and regulations).

Parents have the choice to opt their child out of language services. When parents do opt out, the school is obligated to serve the child as they would any other student, and may offer ESL services in the future if the child is not advancing academically.