We propose a program for developing ethically sustainable cultures in client–vendor relations in information systems development (ISD). The program is based on the participatory design approach and is motivated by the findings of our survey (n = 20) that explored ethical challenges and good ethical practices in the IT field. The data showed that client–vendor relations are ethically conflicting as profitability pressures, for example, induce IS managers to undertake unethical practices. Based on the results of our survey, we identified a dialectical process in client–vendor relations in the form of thesis, antithesis, and synthesis. In the process, impulses inducing questionable or unethical practices (thesis) confront the guidelines for good ethical practices (antithesis). This confrontation between a thesis and an antithesis is implemented through the program we propose, and as a result, morally better practices are expected to emerge (synthesis).