Our purpose in this paper is to shed light on the intricacies of designing and enacting curricular innovations aiming to enhance students' interest in science and their understandings of STEM careers. We present the design and describe the implementation of a set of STEM career-oriented curriculum materials referred to as career-based scenarios. A review of the literature demonstrates that such curricular innovations create potentially useful mechanisms for broadening students' awareness of STEM careers and facilitating more informed decisions. We present the design process we followed to create career-based scenarios and we provide a rationale for each design decision. We also provide a description of the implementation of one representative scenario in three school classrooms. We conclude with a reflective section in which we identify reflections from our experiences and broader implications for curricular innovations targeting students' interests.