Multiple systems have been developed for grading the adverse effects (AEs) of cancer treatment. The National Cancer Institute Common Toxicity Criteria (CTC) system has substantially evolved since its inception in 1983. The most recent version, CTCAE v3.0 (Common Terminology Criteria for Adverse Events version 3.0) represents the first comprehensive, multimodality grading system for reporting the acute and late effects of cancer treatment. The new CTC requires changes in the application of AE criteria including new guidelines regarding late effects, surgical and pediatric effects, multimodality issues, and for reporting the duration of an effect. It builds on the strengths of previous systems, represents a considerable effort among hundreds of participants, and signifies an international collaboration and consensus of the oncology research community. This article updates recent progress in the evolution of adverse effects grading systems and reviews the development of CTCAE v3.0.