The purpose of this study was to deter mine degrees of sibling resemblance from the results of longitudinal testing of intelligence and school achievement. Research data was obtained from ten elementary schools and one junior high school, all in remote areas. Yearly scores from longitudinal tests on the same children served as data for this study. Using the above data we were able to compare siblings of the same age bracket. The main results were as follows:1) Sibling resemblance in school achievement differed according to age;2) Intra-class rs between siblings tended to be higher for contiguous siblings than for noncontiguous siblings;3) Sibling resemblance tended to be greater in verbal IQ than in IQ Performance. These findings indicate that nonshared environmental factors lead to developmental differences between siblings.