The authors have led workshops on the subject for the past decade, sponsored each year by the American Psychological Association, and they have written this text in part as a means of encouraging the use of longitudinal structural equation modeling (LSEM) rather than simpler (inferior) alternatives. Coverage encompasses foundations, LSEM for direct identification of interindividual and intraindividual differences, changes, and determinants. Annotation ©2014 Ringgold, Inc., Portland, OR (protoview.com)