This multi-methods study explores changes in engineering interest and identity of middle and high school students (n = 79) attending introductory-level engineering summer camps at a large western land grant university. Middle school is a critical time when student interest, identity, and subsequently career choice begin to emerge and hence it is important that at this age students are given accurate information about engineering majors in college and future career opportunities in engineering. Data were collected over a period of two years in six summer camps. Three separate populations of middle and high school students participated in the summer camps: (1) Young Women in Engineering camp; (2) First Generation Engineering camp; and (3) Open Enrollment Engineering camp. The study adds to the body of knowledge regarding involvement in informal engineering experiences and the effect on engineering interest and identity for this age group. Pre- and post-surveys as well as focus group interviews indicated a positive change in engineering identity and a strong increase in interest in pursuing engineering majors in college and engineering careers. Four themes emerged from the qualitative data, namely future self as an engineering major and/or engineering professional, enjoyment of camp activities and engineering interest, perceptions and knowledge of engineering, and increase in engineering identity as a result of camp participation in well-structured and purposefully designed activities. Changes implemented in summer camp design based on these themes are discussed.