The main objective of this study is to assess the safety and tolerability of crinecerfont in pediatric participants 3 months to \<4 years of age with CAH.
Have a medically confirmed diagnosis of classic CAH (salt wasting or simple virilizing) due to 21-hydroxylase deficiency (21-OHD)
Have received at least 3 months of hydrocortisone treatment before Day 1, with a stable dose for at least 4 weeks before screening.
Have a body weight of at least 4.5 kilograms (kg) at screening.
Have a newborn screen that is otherwise normal except for elevated 17-OHP or any other abnormality on newborn screen that was cleared upon evaluation by a pediatric specialist.
Have a known or suspected diagnosis of any of the other forms of classic CAH.
Have any condition besides CAH that requires chronic daily therapy with orally administered steroids.
Have any other clinically significant medical condition or chronic disease.