The Science Learning Assessment (SLA) is an individually administered, instructionally sensitive science assessment for kindergarten students. The SLA is a 24-item objective test, broken down into two subtests. The Scientific Inquiry Processes subtest consists of 9 items designed to measure young children's functional understanding of the nature and processes of scientific inquiry. The Life Science Concepts subtest consists of 15 items designed to measure children's understanding of specific science concepts related to living things and the physical world. Our results on SLA items that assess life science concepts indicate that kindergarten children are able to develop a rich knowledge base about living things. The results of the SLA indicate that even young children can begin to develop an understanding of scientific inquiry with appropriate instructional support. Our findings are consistent with recent work by researchers such as Metz (2004), who argue for a richer conception of children's developmental capacities in the context of science instruction. As educators develop new science curricula and programs to address the lack of rich and challenging science instruction in the early grades, there is a need to document what children learn from such efforts. In order to develop research-based and pedagogically effective science curricula, we need assessments with clearly described theoretical and psychometric characteristics. The SLA is one example of such an assessment that can be used to aggregate and compare learning outcomes, as well as to provide empirical information on kindergarten children's capacities for science learning. (Contains 5 tables and 2 figures.)