The purpose of this study was to obtain experts' opinions on parent involvement knowledge of disabled students from the regular classes. Delphi technique was adapted to compile consensus opinions from 39 experts. A self-developed questionnaire named "the parent involvement knowledge of disabled students in regular classes questionnaire" was used and administered to the experts for three rounds in the study. The data was analyzed with means, Kolmogorov-Smirnov one sample test, Mann-Whitney U test, and Kruskal-Wallis one-way analysis of variance by ranks. The findings of this study included: (1) teachers in regular classes played the question finder, opinion reactor, and the partners with parents; (2) teachers in regular classes should have not only specific information on disabled students' family background but also general family knowledge; (3) teachers in regular classes need to have some ideas about parent involvement regulation, proper attitudes, and behavior observation ability; and (4) more practical experiences and diverse instructional strategies were essential for effectively introducing parent involvement knowledge. Therefore, several suggestions, based on the results of the current study, were made in terms of teacher education units and administrators.