While many career development theories (e.g., Gottfredson, in: Brown SD, Lent RW (eds), Career development and counseling: Putting theory and research to work, Wiley, Hoboken, 2005) posit that occupational perceptions are fundamental for understanding youngsters' career aspirations, research relating school students' perceptions of engineers and students' career interest in engineering has been scarce. This study sought to (a) identify the factors underlying the image of engineers to secondary school students, (b) test the invariance of the factors' measurement model across gender and school years, and (c) examine the hypothesis that the factors mediate the effects of engineering experiences at school on students' career interest. Data were collected via a questionnaire from a representative sample of 3724 students at Hong Kong. A measurement model with four latent perception factors (innovation and entrepreneurship competencies; aptitudes related to science, technology, engineering, and mathematics; hands-on work status; and career prestige) fit the responses well and was replicable across gender and school years. Construct validity of the factors was supported by the pattern of their partial mediation effects in the relationship between students' experiences and their career interest in engineering. The results deepened the understanding of the image of engineers and the image's influences on students' career aspiration in engineering. The perception dimensions identified provide a framework useable for engineering education in school.