Target volume delineation is a critical step in the creation of treatment plans in radiation therapy. However, intra-observer and inter-observer variability in target volume definitions can introduce substantial differences in resulting doses between treatments plans from different users and institutions Consequently, there is a need for tools that allow quantitative metrics to be collected and reported regarding inter-and intra-user performance in target volume delineation. We describe TaCTICS, a web-based educational training software application targeted towards residents and non-expert users. TaCTICS allows users to delineate target structures in DICOM-RT compatible formats using their preferred treatment planning system. After uploading the resulting structure file, users are provided a scoring of their structures based on comparison to reference sets derived from expert users using a variety of metrics for volume overlap and surface distances.