[Endometriosis and infertility. A study of 47 cases (author's transl)].

The aim of this two-wave questionnaire study with a 4-week interval among 391 Dutch university students was to test a gain cycle of positive emotions, personal resources, and study engagement. As a theoretical basis, this study drew on the broaden-and-build (B&B) theory and the conservation of resources (COR) theory. More specifically, it was hypothesized that the experience of positive emotions predicts students’ future personal resources and study engagement. Moreover, it was expected that there is a longitudinal relationship between personal resources and study engagement. Furthermore, we hypothesized that positive emotions, personal resources, and study engagement are reciprocally related. Results, obtained by means of structural equation modeling, confirmed both causal (except for the positive relationship between positive emotions and study engagement) and reciprocal hypotheses, thereby successfully integrating the B&B theory with the COR theory.