Across Europe, there is concern about the number and diversity of pupils taking study routes leading to Engineering. There is growing evidence that these career choices begin to form at elementary school age (Moote et al., 2020). Science, maths and design and technology are seen as subject choices necessary for pupils' progression into science, technology, engineering and mathematics (STEM) related occupations. Achievement in these subjects, identity, gender attitudes to the subjects, parents and informal activities may have an impact on these career choices. This mixed methods research draws on participants in the Children as Engineers project to investigate aspirations to a career in engineering and the links between these aspirations and attitudes to STEM subjects. It explores findings that suggest that there is little relationship between aspirations and positive attitudes to individual curriculum subjects. Pupils' out-of-school activities and the links to aspirations in engineering are also researched and discussed. The article discusses the pupils' rationales for these choices and the implications for intervention and informal engineering experiences that rely on a science and maths context for elementary school activities and for fostering interest in engineering.