The NSF-funded LOCUS project (DRL-1118168) has developed assessments to measure conceptual understanding in statistics, different from the procedural knowledge commonly assessed. This session provides a brief description of the development of the assessments, which are aligned with the GAISE framework and CCSS-M, and a number of representative sample items. Since statistics is a tool utilized in scientific exploration, LOCUS has implications for research and teaching of mathematics and science. This session will also highlight how sample items can be used in professional development with teachers.