Joel M. Hektner is an Associate Professor in Human Development and Family Science at North Dakota State University. He holds a Ph.D. in Psychology: Human Development from the University of Chicago and an A.B. in psychology from Princeton University. Before arriving at NDSU, Hektner was a research scientist in child and adolescent psychiatry at the University of Minnesota. He has used ESM to study the developmental implications of longitudinal changes in adolescent experiences of flow and has written chapters on ESM in several books. In collaboration with students, he has conducted ESM studies