Since the Tarasoff decision by the California Supreme Court in 1974, mental health clinicians have struggled to balance their duty of confidentiality to their patients against the duty to protect third parties from potential violence. This article explores the development of this issue over the last 20 years, with a focus on ways that Tarasoff has and has not affected clinical practice. Reviewing the evolution of case and statutory law, we discuss appropriate clinical responses for the mental health practitioner who faces a potential "duty to protect" situation.