The transformation processes of 1989 initiated Central European countries’ aspirations to integrate with Western Europe. In response, the world’s leading industrialized nations pledged support for systemic transformation, leading to the European Community’s establishment of the PHARE program in 1989 for Poland and Hungary. Over time, this assistance expanded to other aspiring EU member states, forming a coordinated pre-accession strategy.A key financial instrument within this strategy was the Instrument for Structural Policies for Pre-Accession (ISPA), introduced in 2000. Modelled on the EU’s Cohesion Fund, ISPA aimed to support economic and social cohesion through large-scale investments in environmental protection and transport infrastructure. The program facilitated compliance with EU environmental standards and the development of trans-European transport networks (TENs). In Poland, ISPA-funded projects improved air and water quality, waste management, and integrated national transport systems with EU networks.The literature on the use of pre-accession funding and ISPA in particular is fragmented and not abundant. Therefore, this article sheds light on ISPA’s programming, application processes, implementation challenges, and outcomes in a comprehensive way. The study employs legal analysis, critical evaluation of reports, and statistical data to assess ISPA’s performance. The findings provide insights into optimizing pre-accession assistance mechanisms and guiding future EU cohesion policy funding. It also serves as a source of policy-learning for the prospective EU Member States.