A randomized trial of the multisite evaluation of the Parents as Teachers home visiting program indicated significant attrition from program services and wide variation in participation and involvement of the families. This exploratory study of parental engagement reflects a growing emphasis in the field on research related to implementation issues. Based on qualitative data from site visits with program staff and parents, the authors developed a model of five proposed dimensions of engagement. They examined quantitative data that served as indicators of the dimensions and explored parent and family factors that related to each type of engagement. The results indicated that it is both appropriate and useful to characterize parental engagement in home visiting programs as a multidimensional concept that goes beyond simply enrolling or dropping out. The data suggest that some dimensions of engagement are independent of others and that different parent factors relate to different types of engagement. The implications for future program evaluation, as well as for training and supervision in home visiting programs, are discussed.