Evaluations of HIPPY have shown that it achieves mixed results. For example, in a study in New York state, a total of 182 families in two different cohorts were randomly assigned to receive the intervention or to be in a control group. The intervention families were in HIPPY for two years, and children in both the experimental and control groups were in high-quality, full-day preschool programs during the first year and kindergartens the second year. In cohort I, HIPPY children performed better than control group children on measures of cognitive skills at the end of kindergarten and on a standardized reading test at the end of first grade. However, none of these effects were found for cohort II. In trying to determine what could have caused such different outcomes for the two cohorts, the authors posit that varying levels of parent involvement were to blame. In home visitation programs, attrition, canceled appointments with home visitors, lack of (or waning) enthusiasm and not sticking to the prescribed schedule of parent-child activities can be problems. The authors suggest that levels of parental involvement need to be carefully documented in future evaluations of HIPPY (Baker, Piotrkowski, & Brooks-Gunn, 1999). While home visitation programs are promising as a means of increasing a parent's ability, confidence and desire to help her child develop emergent literacy skills, ways to foster enthusiastic parent participation must be considered in order to implement successful interventions.