The growing diffusion of software in society and its influence on people demands from its creators that their work carefully considers human values such as transparency, social responsibility, and equality. But how do software practitioners address human values in software engineering practice? We interviewed 31 software practitioners from two organizations, each having a strong values framework, with the aim to understand: (a) practitioners’ perceptions of human values and their role in software engineering; (b) practices that practitioners use to address human values in software; and (c) challenges they face during this process. We report our findings from two contrasting case studies on how practitioners “engineer” values in their unique organizational settings. We found evidence that organizational culture significantly contributes to how values are addressed in software. We summarize recommendations from the practitioners to support proactive engineering of values-conscious software.