The Educational and Career Interest scale, a self-report instrument measuring high school students' educational and career interest in STEM, was developed and validated in two studies conducted during 2010 and 2011. Study 1 included data from 92 high school students, in which exploratory factor analysis (EFA) was conducted with an initial item pool of 20 items. EFA identified three factors: educational and career interest in science, educational and career interest in technology, and educational and career interest in mathematics. Study 2 utilized data from 658 students to revisit the three-factor model using confirmative factor analysis. The two studies provide strong evidence that the scale is both valid and reliable.