Abstract: When a professional is negligent in providing services to her client or patient, third parties are sometimes harmed. “Triangular torts,” as we call them, are negligence claims brought against professionals by such third parties. One common example involves a father suing a therapist for inducing his daughter to have false memories of childhood abuse, thereby causing him emotional harm. Another involves a nephew suing a lawyer for incorrectly drafting his aunt’s will, thereby causing him financial loss. Despite the general decline of privity limits on negligence liability, courts frequently reject triangular tort claims, ruling that professionals do not owe duties of care to third parties. In this chapter, we explain when such rulings are warranted — and when they are not. The answer turns on whether the recognition of a duty of care to the third party is consistent with the professional’s fiduciary duty of loyalty to the client or patient.