To enhance concern for the social aspects of sustainability and to delineate the criteria to be considered at each stage of the lifecycle of an infrastructure, this paper aims to determine the relevance of a set of criteria that evaluate social sustainability throughout the lifecycle of a public civil infrastructure. This research presents the results of a case study applying the Delphi method to 24 Chilean experts consulted in a series of three rounds. In addition, binomial statistical tests and Kendall’s coefficient were used to show the convergence of the experts. Thus, it was identified that of 36 initial criteria assessed at each stage of the lifecycle, the consideration of 20 is required at the design stage, 29 at the construction stage, 33 during operation, and 27 at demolition. The most relevant criteria, per lifecycle stage, were Stakeholder Participation (design and demolition stages), External Local Population (design stage), Internal Human Resources (construction and demolition stages)...