The construct of sexual grooming has achieved substantial legal, clinical, and policy influence over the past three decades, yet the empirical foundations upon which this influence rests remain significantly underdeveloped. This article presents a systematic critical review of the peer-reviewed literature on sexual grooming, examining four interconnected areas of scholarly concern: definitional inconsistency across research and legal contexts; methodological limitations in the empirical evidence base; conceptual boundary problems between grooming behaviors and normative relationship initiation; and the neurodevelopmental assumptions embedded in age-based vulnerability frameworks. Drawing on published critiques from criminology, developmental psychology, social work, and legal scholarship, this review argues that the grooming construct as currently operationalized in research and applied in law and clinical practice lacks the definitional precision, measurement consistency, and empirical rigor required of constructs with such significant legal and social consequences. The review does not contest that predatory exploitation of vulnerable individuals occurs and causes serious harm. Rather, it argues that the scientific and legal utility of the grooming construct depends on the resolution of foundational definitional and methodological problems that the field has not yet adequately addressed. Implications for research design, legal application, clinical practice, and policy are discussed.