New and recently established systems for regulating competition are often prone to an institutional instability, weak authority, and fragile track-record. Their development negotiates a variety of lifecycles, with various factors impacting their evolution. Relying on competition system development literature to provide a theoretical framework for our research, an empirical qualitative research study was conducted with the aim of examining the competition system in Croatia, in the 1995-2018 period. Main stakeholders were interviewed (in-depth interviews), forty persons in total (NCA officials, judges, practitioners, corporate lawyers, journalists, and academics). Archival research, as well as online research, was conducted to find relevant press reports, and selected NCA quantitative data was analysed. Using content analysis software, original and valuable insights were drawn from this dataset. The aim is to develop a theory that is able to explain the reasons underlying competition system immaturity in Croatia, more than two decades after its creation. The findings include a specific evolutionary path, as well as two underlying issues. Four distinct phases of development were identified (Inception; Withdrawal; Pre-accession; and Post-accession phase). The underlying issues are, first, a lack of institutional and system embeddedness, and second, functional self-restraint on the side of the authority, arguably a result of negative institutional memory. The comprehensive dataset and methodology used, make this research distinctive in broader terms, including being the first such study conducted on Croatia. This paper aims to contribute to the broader literature on competition systems development by examining the relevance of specific factors influencing their evolution