Efforts are underway to determine if there are any ways unique to Navajo thinking and thus to the way that they might learn. Studies have shown a consistent lag in achievement levels for Native Americans. The purpose of this investigation was to examine spatial thinking abilities of sixth and tenth grade students from 2 locales—a school on the Navajo Reservation and schools in Mesa, Arizona. A battery of 10 Piagetian-type tasks were administered individually to the subjects. A chi-square one sample procedure was used to test for significant differences between subsamples at each grade level. Significant differences were detected for two of the tasks at the sixth grade level, and one task at the tenth grade level. The overall findings of this study support the contention that there were no substantial time delays or advances in the development of selected spatial abilities of Navajo sixth and tenth grade students compared to those of parallel non-American Indian students. The concern of modifying instruction in science courses in order to adapt them to supposed 'different' spatial structures possessed by Navajo students appears to be unfounded.