Considerable effort has been spent on interventions to increase the numbers/diversity of young people studying Science, Technology, Engineering and Mathematics (STEM) and/or entering STEM related careers with little evidence of their effectiveness. In the UK, less than 10% of professional engineers are female. Science capital is a recent concept for capturing those elements that influence children’s choice of a science-related career. Children with higher science capital are more likely to choose a STEM career than those with lower science capital and therefore interventions to increase science capital are needed. Initially studies evaluating science capital have focused on secondary age children (aged 11 – 18 years). Here a research approach for evaluating science capital among primary age children (aged 7 – 11 years) is presented using a mixed methods approach. Results indicate that children share similar perceptions of scientists as ‘hardworking’, ‘clever’ and ‘creative’ independent of gender, age and science capital. However, children’s self-identify differed by gender, age and science capital, illustrating significant gaps for some children between their self-identity and that of a scientist. Interventions focusing on narrowing this gap should increase the likelihood of them considering a science-related career.