The purpose of this study was to investigate the relationship between developmentally appropriate practices (DAP) and parental involvement beliefs of preschool teachers and the parents of preschool children. Data were collected from 279 teachers and 589 parents via a demographic information questionnaire, Teachers' Beliefs Scale [Jones, L. D., Burts, D. C., Buchanan, T. K., & Jambunathan, S. (2000). Beginning prekindergarten and kindergarten teachers' beliefs and practices: Supports and barriers to developmentally appropriate practices. Journal of Early Childhood Teacher Education, 21, 397-410]; Parents' Beliefs Scale [Yen, Y. (2008). Parents' beliefs about developmentally appropriate practice in early childhood programs in Taiwan (PhD thesis). Retrieved from ProQuest Dissertations and Theses database (UMI No.3352157)] and the School and Family Partnerships Questionnaire [Epstein, J. L., & Salinas, K. C. (1993). School and family partnerships: Surveys and summaries. Baltimore, MD: Center on School, Family, and Community Partnerships, John Hopkins University]. The results underline the relationship of parental involvement beliefs of teachers and parents with their DAP and Developmentally Inappropriate Practice (DIP) beliefs, as well as providing that DAP or DIP beliefs are not independent in their nature; they are influenced by parental involvement beliefs. (author abstract)