The administrative appeal is a multifunctional legal remedy whose purpose is to protect the rights of the parties vis-à-vis the authorities and provide – through a generalisation of cases – a regulatory feedback loop leading to better sector-specific regulations. The administrative appeal is thus a constitutional guarantee of democratic governance, as well as mechanism of good administration and effective public policies, as long as it is implemented in line with the purpose of regulation. To examine the theoretical and regulatory objectives of the administrative appeal in Slovenia and Croatia and test its compliance with EU trends, a comparative analysis of the key provisions of the systemic laws on the general administrative procedure (APAs) was carried out. In such context, specific effectiveness criteria were developed, focusing on the admissibility, devolution and suspensiveness of the administrative appeal, as well as on the duration of the administrative appeal procedure. The achievement of the regulatory objectives of the APAs in both countries was further examined through interviews with experts in administrative procedural law and, for Slovenia, through an analysis of administrative case law. The finding suggest that the most challenging issues are the (non-)suspensiveness of the appeal and the duration of procedure. Hence, the administrative appeal may well be a fairly suitable safeguard of the constitutional rights of the parties in individual cases, but on a systemic level, its potential for good administration is not fully exploited. This instrument should therefore be further developed, e.g., through a mutatis mutandis application of the APA in all administrative acts and an even more consistent application in the most disputable administrative procedures, particularly in terms of the suspension of enforcement pending administrative finality and the still reasonably long procedures. The key points for practitioners are: • The administrative appeal has various functions, such as protecting international and constitutional safeguards of the parties to the procedure and ensuring a coherent administrative-legal system / • In the EU, procedural issues in individual Member States can largely be regulated autonomously / however, there are certain characteristics necessary to define the appeal as an effective tool / • Slovenia and Croatia regulate the administrative procedure in a rather similar way, yet there are some crucial differences in effectiveness of the administrative appeal both in law and, particularly, in practice / • Experts, especially from the CEE region, can learn about the gap between theory and practice in the selected countries, which enables them to compare other similar national systems in line with the EU standards.