Background: Community-engaged learning initiatives in engineering often struggle to achieve equitable outcomes for community partners because students in such programs often possess a design-for-charity mindset, which is characterized by an uncritical desire to help and the design of solutions that address symptoms of inequity without meaningful community involvement. The paradigm of design-for-justice seeks more equitable outcomes by illuminating positions of power, leveraging community knowledge, facilitating community participation, and altering the structural causes of inequity. Purpose: Little is known about how to support students in developing a design-for-justice mindset. This work investigated how students in one particular community-engaged engineering program with a social justice orientation learned to shift mindsets from charity toward justice. Method: I conducted a case study of a community-engaged engineering learning project during a single academic term using participant observations and semi-structured interviews of eight undergraduates with varying levels of project experience. I performed thematic analysis to identify learning processes students employed in making mindset shifts. Results: Students employed four primary learning processes in developing and deepening a design-for-justice mindset: (1) drawing upon prior experience with inequity; (2) connecting to course content; (3) imitating experienced team members; and (4) empathizing with community members. The three core elements of the program experience--introductory course, laboratory course, and field practicum--each fostered shifts along distinct mindset dimensions. Conclusion: This research offers insights into creating community-engaged engineering learning experiences that may help students shift toward a design-for-justice mindset and has broader implications for how all engineering students might develop socio-technical thinking skills.