Abstract
The objective of this paper was to conceptualise the issue of cooperation stability in research on cross-border cooperation. On this basis, regularities related to selected aspects of the stability of cross-border cooperation were identified using the example of the Polish border regions. The analysis was based on a complex review of the Interreg, ETC, ENPI, and ENI cross-border cooperation programmes implemented in the Polish border regions between 2007–2013 and 2014–2020, taking into account both internal and external EU borders. The study covered a total of 1,577 projects realised between 2007–2013 and 2014–2020 by more than 4,500 beneficiaries, comprising 2,307 organisations. A survey of these organisations was also conducted. The resulting analysis helped to identify the relative stability of partner types and the thematic scope and spatial dimension of cross-border cooperation, while at the same time revealing a lack of stability in the organisational dimension. In addition, the study showed that the initiation and subsequent maintenance of cross-border relationships are the result of a complex process, in which many factors co-exist simultaneously, whereas the break-up of cooperation can be the product of individual factors.