Educational researchers have long noted the apparent link between positive student attitudes and a student's desire to continue their study of particular subjects beyond the compulsory years of schooling, with much of the research motivated by concerns around declining student participation rates in high-school and university. However, unambiguously measuring students' attitudes is notoriously difficult. In addition, the question of which attitudes have the most significant effect on student intentions is not fully understood. This study was designed to address the gap in understanding between students' attitudes and their enrolment intentions by surveying a large cohort of Australian students at regular intervals during their first year of high-school (Year 7, aged 12-13 years). An innovative, new digital instrument was used to gather quantitative data about students' attitudes towards school subjects across seven constructs. Subject Attitude Profiles were then constructed for the disciplines of science, mathematics and design technologies and compared with each other and also with a Composite Attitude Profile for all school courses. We show that although students' attitudes to the STEM subjects vary widely, their attitudes generally decline over the first year of high-school with regard to a number of attitudinal constructs. We also show that the trends within these STEM disciplines are not identical and we therefore conclude that each discipline requires an individual response if students' attitudes are to be addressed.