Classification policies and evaluation tools can vary widely from state to state, and even district to district, leaving widespread opportunity for error.
The study found that the quality of early-childhood teachers' English use is more important than the quantity for developing language skills in young ELLs.
"The Condition of Latinos in Education: 2015 Factbook" pulls data from a number of sources to a give state-level picture of K-12 enrollment and shed light on national advances and challenges for Latino students.
The programs will include instruction in Mandarin, French, Haitian Creole, Hebrew, Japanese, or Spanish, depending on the school site.
An Education Commission of the States report outlines each state's funding mechanism for ELLs, along with differences in dollar amounts and teacher allocations across the states.
The guidance comes on the heels of the recent 40th anniversaries of Lau v. Nichols, a landmark Supreme Court decision, and the Equal Educational Opportunities Act of 1974, both of which expanded rights of students with limited English proficiency.
Former Arizona Superintendent of Public Instruction John Huppenthal deemed several courses illegal during his final hours in office, leaving one of the state's largest school districts facing a possible funding loss of $14 million annually.
Federal officials granted the state's request to give its English-language learners two years in a U.S. school before counting their test scores in school grades.
Many students struggle to learn English because schools fail to monitor their progress, adequately train teachers or provide appropriate curriculum.
New policy prohibits schools from asking about the immigration status of students or their families during the enrollment process and provides guidance on the range of documents students may use to prove residency.