An Innovator and a Disruptor: Leonard Bickman on Program Theory, Null Findings, and Advice to Future Child Mental Health Services Researchers.

With a career spanning more than half a century, Leonard Bickman has contributed to improving children's mental health through research on innovative interventions, such as measurement-based care, and service-level initiatives, including systems of care. Len's highly productive career in children's mental health services research is founded in his influence on the science of program evaluation, particularly in the area of program theory. This article provides an abridged and combined version of a video interview with Len dated April 16, 2019 and written responses to a series of questions posed to Len in advance of the festschrift held in his honor at Johns Hopkins Bloomberg School of Public Health on May 11, 2018.