Background - Early adulthood is the developmental stage during which, for the first time, an individual can independently choose their own lifestyle. For the future health of a young adult, it is important that they incorporate healthy behaviors from different health dimensions into their lifestyle. Analyzing the foregoing issue gives rise to a fundamental question: did intensive social changes experienced after Poland’s accession to the European Union lead to changes in different aspects of a healthy lifestyle? Method - The presented (...) study involved 504 people. The research data was collected in two separate measurements in 2003 and 2013. Subjects were asked to complete sets of questionnaires which measured: health behaviors, health beliefs, social influence, intention. Results - Statistical comparison of means tests and regression equations were conducted. Results demonstrate that young adults were similarly engaged in pro-health activities in both 2003 and 2013. A detailed analysis of health lifestyle factors shows that young adults from the 2013 group care more about their diet, physical activity, and more frequently undergo preventive medical health examinations. Moreover, significant changes in healthy lifestyle factors were reported. The most important observation concerned the changes in health beliefs. Beliefs derived from a holistic-functional model of health played a major role in the 2003 group, whereas in the 2013 group beliefs close to the biomedical model of health were more important. Conclusions - Analyses demonstrate changes in detailed healthy lifestyle factors. At the same time, no significant differences in global measures of concern for one’s health were observed. Importantly, results show modifications in healthy lifestyle factors. It is suggested that the observed differences stem from the social change of the last decade. (shrink)