The purpose of the present study was to compare the health status of children aged between 6 and 12 years reared by grandparent and parent, including the factors affecting the development of both groups. A cross-sectional study was conducted in 2 different caregiver groups, 160 children living with their grandparents and 160 children living with their parents in Phrae province. The samples were selected by cluster sampling and data were collected from March 10 to April 8, 2006 by questionnaire. The Test of Nonverbal Intelligence-3 was used to test the child development. Data were analyzed by frequency distribution, percentage, χ(2) test, and multiple logistic regression. The illness in the past 6 months and nutritional status of the children aged 6 to 12 years were not different between 2 groups, but the child development and appropriateness of child rearing were different with statistical significance (P < .05). Children who were reared by grandparents had a higher percentage (66.7%) of below normal development than those reared by parents (33.3%), and had inappropriate child rearing by a rate of 57.7% compared with 42.3%. In addition, the factors affecting the development of children reared by grandparents were both the level of the family income and the child rearing factor, whereas the child development in those who were reared by parents was affected only by the child rearing factor.