Like many other Central and Eastern European countries Croatia has passed through substantial political changes and transition processes from state to liberal market economy in the last two decades. The next important step is accession to EU and NATO, and public opinion about joining these associations is divided. The aim of this study is to investigate the predictive value of subjective well-being measures in explaining attitudes of Croatian citizens toward accession to NATO and European Union. In particular, the prognostic utility of SWB is tested over and above usefulness of basic socio-demographic variables in explaining those political opinions. The research was conducted on a huge and representative sample (N = 4,000) of Croatian citizens in the spring of 2009. As a measure of subjective well-being, Croatian version of International Well-Being Index (IWI; Cummins in International Wellbeing Index, Version 2 [online]. Available from: http://acqol.deakin.edu.au/inter_wellbeing/Index-CoreItemsDraft2.doc , 2002) was used. IWI includes National and Personal Well-Being scales where each scale consists of several personal or national well-being domains. Socio-demographic variables used in this survey were gender, age, and level of education. Hierarchical logistic regression was applied to test the unique contribution of National and Personal well-being domains in predicting attitudes toward accession. The results show that National well-being index is useful in predicting attitudes toward accession of Croatia to EU and NATO, and has an even higher predictive value than basic socio-demographic variables. National well-being domains that significantly improve prediction were satisfaction with government and satisfaction with national economic situation. Higher satisfaction with national government is related to support of accession to both alliances, whereas higher satisfaction with national economy is associated solely with supporting the EU membership. The personal well-being index and belonging domains were not useful in this political attitude prediction. Possible theoretical explanation of observed relations between NWI and political opinion were further discussed.