Student labs are out-of-school learning environments that are assumed to promote students‟ interest in science. They are characterised by aspects of situated and authentic learning, a prominence of application contexts presented by scientists, and a high amount of practical work. Research has shown the potential for promoting students‟ interest in science for each of these aspects when implemented separately as a teaching approach in science education. This study aims to explore, whether (i) these aspects can be shown to be separately effective on students‟ interest even when realised jointly in the learning environment and, if so, (ii) which reciprocal effects can be shown with regard to students‟ attributes (prior individual interest, self-concept, gender) and the degree of pre-visit instruction in school. A questionnaire was developed based on interest theory and theories of interest development. A total of 378 upper secondary students completed the questionnaire. A factor analysis indicated the students‟ interest in the lab to be three-dimensional with the factors having a strong relation to (1) experiments, (2) application contexts of research, and (3) authentic learning environments. Structural equation modelling dictated significant interrelationships between students‟ interest in the student lab and students‟ attributes (e.g. prior individual interest in science), the degree of pre-visit instruction in school and the quality of instruction in the student lab. The analytical framework used in this study is based on theories of interest development by considering the basic needs as mediator variables and offers a means of assessing students‟ interest in out-of-school settings.