In this review, controlled clinical trials of acupuncture are placed into five categories on the basis of the treatment with which acupuncture is compared. Methodological and ethical issues relevant to each category are discussed. Wait list (or no treatment) controls, which are ethically acceptable for stable, chronic conditions, assess the efficacy of acupuncture relative to the natural history of the condition but do not control for nonspecific treatment effects. Placebo controls, defined here as noninvasive procedures such as inactive transcutaneous electrical nerve stimulation (TENS) or mock needling, assess whether acupuncture has an effect beyond that of the therapeutic milieu. Sham controls, defined as invasive but inappropriate procedures such as shallow needling at nonacupoint sites, assess whether acupuncture efficacy depends on the style and location of needling. Standard care comparisons assess whether acupuncture performs at least as well as a medication, medical device, or physiotherapy. Adjunctive care comparisons assess the efficacy of acupuncture plus standard care relative to standard care alone. From an ethical perspective, active debate surrounds placebo and sham controls. Those who argue against these procedures consider withholding treatment to be improper. They favor the wait list and both standard care designs in which all patients receive treatment. Others argue that testing a treatment prior to demonstrating its efficacy against a placebo is equally improper. From a methodological perspective, it should also be considered that most clinical trials of acupuncture have assessed its efficacy by administering a fixed course of treatment based on biomedical diagnosis. The challenge for future trials is to design conditions that more closely mimic the delivery of acupuncture in clinical practice, as individualized treatment informed by its own diagnostic traditions.