Study provides insight about development, mental health of underserved ethnically diverse children A study in the Journal of the American Academy of Child and Adolescent Psychiatry (JAACAP), published by Elsevier, reports on the young adult assessment of the now 20-year longitudinal Boricua Youth Study (BYS), a large cohort that brings much needed insight about development and mental health of children from diverse ethnic background growing up in disadvantaged contexts. The present article, with its companion report on prevalence of conditions and associated factors, provides an update on the study's fourth wave, which follows-up two probability-based population samples of children of Puerto Rican heritage. Unique to the study is its two-site design, which allows for comparison of a single ethnic group in two contexts: one in which the group is an ethnic minority living in an disadvantaged area (South Bronx, NY); and another where though challenges are many, children do not grow up being part of an ethnic minority group (San Juan, Puerto Rico).