Given the increase in novel agents and difficulty with planning and completing many phase III studies, various phase II trial design options should be considered to more effectively guide phase III trial plans. The need for novel phase II trial designs has increased, given the number of novel molecular targeted therapies now available for testing, an abundance of cytostatic agents, and limited resources to conduct phase III studies for all interesting agents or combinations. This review will focus on options for phase II trial designs. We review randomized phase II designs with placebo control, randomized selection designs, and randomized discontinuation designs. As agents become available for testing in the clinic, the strengths and weaknesses of different phase II trial designs should be considered to optimize a trial development plan that guides phase III trial decisions more effectively.