Monoclonal antibodies (mAbs) comprise the majority of protein candidates currently in clinical development because of their versatility as therapeutic agents. While traditionally associated with the biotechnology industry, mAb therapeutics are now being developed and marketed by most major pharmaceutical firms. A total of 21 products are approved in the US, with additional products marketed outside the US, and over 200 mAb candidates are currently undergoing clinical study. Benchmark data for mAb therapeutics, such as clinical development and US Food and Drug Administration approval times, approval success rates, and clinical phase transition probabilities, are critical for strategic planning purposes. Trends in these benchmarks for various types of mAbs, with an emphasis on those studied as anticancer and immunological therapeutics, are discussed.