Previous research on grandparents has focused on the individual and familial level and has characterized grandparent roles as ambiguous and contingent. Emphasizing instead structural phenomena, this theoretical paper argues that grandmother and grandfather roles are being institutionalized through state and federal legislation. This phenomenon provides an opportunity to investigate the process of institutionalization as it happens. Grandparenthood is evaluated as a potential site for institutionalization and law as a source of institutionalization is discussed. Preliminary evidence of the legal institutionalization of grandparenthood is presented and implications and directions for further research are suggested. (Contains 1 footnote.)