The Istrian Democratic Assembly is one of the more successful regional parties, and dominates the extremely developed Istrian region, one of the most developed in Croatia. This research analyzes the operation of IDS from 1991 to 2023. During the analysis, special attention was paid to changes and adaptations of party activities to political circumstances in the environment. The analysis itself is linear and based on data collected from several forms of sources: scientific papers, official party documents, interviews and other publicly available materials. The analysis is approached in two ways, which is immediately visible from the construction of the research question: "How and why did the politics of the Istrian Democratic Assembly change in the period from 1991 to the present day?" So, the paper problematizes both the causes and consequences of changes in the politics of the IDS party. In the period from 1991 to 2023, the party changed three presidents, but its policies did not change much. The party maintained its commitment to the preservation of the Istrian identity, economic development and European integration, its politics adapted to new circumstances and challenges brought by political and social circumstances, and it represents a significant example of regional politics in Croatia and beyond.