The contribution of parental involvement in the parent-teacher association (PTA) to schoolchildren's performance is an issue for evaluation research. To resolve the issue, it is reasonable to differentiate people who benefit and others who do not benefit from the involvement. Such differentiation relied on survey data from 289 pairs of Hong Kong Chinese parents and their children between Grade 4 and Grade 9. It revealed that only 28.8% of the parent-child pairs had their child performance benefiting from the help of parent-teacher associations (in terms of a standardized effect of 0.2). Factors predictive of this minority subgroup were the child's grade and having a single parent. These factors tend to identify the need for help from parent-teacher associations, which can be a consideration for planning effective help from the associations. (Contains 6 tables and 1 figure.)