According to LEP.gov, individuals who do not speak English as their primary language and who have a limited ability to read, speak, write, or understand English can be limited English proficient, or "LEP." For funding and service purposes, there may be additional layers of specification to be considered. Let's consider the following: LEP household and LEP individual.
Language use, English-speaking ability, and data on limited English-speaking households are currently collected in the American Community Survey (ACS). An "LEP household" is one where no The definition of “limited-English-speaking household,” as used by the American Community Survey (ACS) is “a household unit where no member 14 years old and over speaks only English at home or speaks a language other than English at home and speaks English less than ‘very well.’” Whereas an "LEP individual" is anyone five (5) years old and over who speaks a language other than English at home and speaks English less than ‘very well’.
Bear in mind, language use data is collected on a self-reported basis via government form/survey. Individuals who speak a language other than English in the home choose to self-report the language they speak, but are also asked to make a "ballpark" assessment about their English proficiency.
Due to decades of policies that sought to limit bilingual education and the use of non-English languages, entire generations of children of immigrants did not learn the mother tongue of their parents, leaving many individuals feeling disconnected from their family and culture.