The ABCD Study has enrolled nearly 12,000 students and their families from all over the country. The participants reflect the U.S. population of boys and girls and include students of diverse races and ethnicities, education and income levels, and living environments. Enrollment is now complete.
During the participant enrollment phase, selected schools provided information packets about the study to all the families of 8-, 9-, and 10-year-old students.
Families were contacted by a researcher at the nearest university who determined whether a child was eligible. If so, families were contacted again to set up appointments, and were provided instructions for what to expect and directions to the appointment. Participants and families are compensated for the time spent participating in the study.