Spanish students' beliefs on themes of Science-Technology-Society (STS) and nature of science (NOS) are assessed. The sample consisted of 1050 science and non-science students who had concluded their pre-university education (18-19 years old). Each participant anonymously answered 30 items drawn from the Questionnaire of Opinions on Science, Technology and Society, which were presented within two different booklets to cover the main STS-NOS issues. The students’ direct responses were scaled by means of a multiple response model and a metric into a set of quantitative indices that represent the adequateness of the student’s answer to current scholar knowledge on STS-NOS. The indices form the baseline variables on items, categories, and sentences for the quantitative and qualitative analyses of students’ beliefs. The overall mean results display neutral positions, although a detailed scrutiny of the mean indices across items, categories, and sentences allows to pinpoint further rich details, such as the students' highest positive and lowest negative beliefs to be identified. The versatility of the method makes also possible to implement hypothesis testing, which in the present case do not find significant differences between science and non-science students. Some implications for research on the issues concerning the STS-NOS issues and its teaching and learning are discussed.