Should Heritage Languages be Incorporated into Interventions for Bilingual Individuals with Neurodevelopmental Disorders? A Systematic Review.

Lee et al. (2019) looked at 18 studies that compared therapy in a child’s heritage language versus English-only. All studies involved kids with autism or other developmental disabilities who heard two languages at home.

The team asked one question: Does adding the home language to sessions help or hurt learning?

Across the 18 studies, kids did slightly better when the therapist used the heritage language. The edge was small but showed up again and again.

No study found harm from keeping the home language in play.

Lim et al. (2018) ran one of the experiments inside this review. They saw more play acts when therapy was in Spanish instead of English, matching the small boost the review reports.

Clay et al. (2020) looked at praise language and found mixed results—most kids did not care if the praise was English or Spanish. That single-case focus on reinforcers sits inside the bigger picture: heritage language does not hurt and may help.

Kim et al. (2024) updated the same question for U.S. schools and clinics. They found the same small benefit, showing the 2019 result holds true in American systems.

You do not need to push English-only sessions. Letting parents speak their home language during parent training, or using simple heritage words during play, gives a free, tiny lift in learning. Start by asking families which language feels easiest for daily routines and sprinkle that language into your prompts and praise.