Administrative review is the process by which an administrative decision made by a public official—for example, to refuse benefits or immigration status—is reconsidered by a different official within the same public body. Administrative review has operated in various contexts for years, but the rate of its recent expansion has been remarkable. Two systems have been key to this rapid growth. In the social security context, the introduction of “mandatory reconsideration” requires that claimants refused benefits must first seek an administrative review before appealing to a tribunal. In immigration, long-established appeal rights have been replaced entirely by administrative review. The volume of disputes channelled through administrative review exceeds that of tribunals and makes judicial review appear esoteric. This is a radical change to how people access and experience justice in thepubliclawcontext.Forthelast50yearsandmore, individuals in receipt of a negative administrative decision could appeal directly to independent and judicial tribunals to determine their legal rights and entitlements. The rationale for this fundamental shift is clear: the increase in tribunal caseloads and the success rates for appellants, austerity, and political objectives (the desire to reduce social security spending and immigration rates) have prompted the government to reduce the number of tribunal appeals by requiring individuals to use administrative review. Within the longer arc of administrative justice developments, we suggest that administrative review should be understood as a consequence of the progressive judicialisation of tribunals. Government departments have argued that administrative review can provide people with an efficient and quicker way of correcting case-working errors and there by reducing unnecessary appeals. On the other hand, there are concerns that administrative review is often an ineffective mechanism for challenging administrative decisions. This article argues that administrative review—as it currently operates—is a problematic response to the increased judicialisation of tribunals. Administrative review has largely weakened the ability of people to secure redress. Reforms are, therefore, necessary to ensure administrative review can work more effectively in practice. The first part of this article discusses the need for justice within administrative decision-making and the development of tribunals. The second part turns to the recent expansion of administrative review. The third part considers the practical operation of administrative review in both the social security and immigration contexts. The fourth part assesses administrative review and suggests ways of enhancing its effectiveness. The final part considers the wider constitutional implications of the growth of administrative review. In particular, we suggest this episode of de-judicialisation provides an insight into the nature of judicial power in UK public law. In contrast to the standard, high-profile debate about the growth of judicial power and the rise of “juristocracy”, the recent experience of administrative review tells a different tale. The greater use of administrative review has gone hand-in-hand with a correspondingly smaller role for the judicial control of front-line administrative decisions.