CATCH: challenges of conducting process evaluation in a multicenter trial.

This paper discusses the challenges faced when collecting process evaluation information in a school-based, multicenter field trial. Experiences from the Child and Adolescent Trial for Cardiovascular Health (CATCH) are shared as a means of illustrating the challenges that are presented and ways of meeting the challenges. The scope and magnitude of the trial (96 schools across four sites) and the diverse population participating in the trial (including children and adults representing a cultural and socioeconomic mix) present challenges that are compounded by conducting research in a highly structured school setting. In such a trial, thoughtful consideration must be paid to what data should be collected, how data should be collected, how to collect data on tailored interventions, gaining and maintaining schools' cooperation, collecting data in year-round schools, and assuring data quality.