This study investigated the use of block-building interventions to develop spatial-reasoning skills in kindergartners. Two intervention conditions and a control condition were included to determine, first, whether the block building activities themselves benefited children's spatial skills, and secondly, whether a story context further improved learning. Spatial measures included: spatial visualization, mental rotation, and block building. Results showed: for block building, interventions within a story context improved performance compared to the other two conditions. For spatial visualization, both types of block-building interventions improved performance compared to the control condition. Findings suggest: (1) storytelling provides an effective context for teaching spatial content, (2) teaching block building develops wider spatial skills, and (3) 3-dimensional mental rotation tasks show a male advantage in kindergartners. (Contains 4 tables and 4 figures.)