In this article, we describe and illustrate a five-step process model for designing practice scenarios for digital simulation-based conversation training, in which learners practice challenging conversations with a virtual character. To maximize the likelihood of a successful learning experience, it is important that these practice scenarios are perceived as authentic by learners, and that they are based on relevant theory and validated expertise from experienced professionals. Our process model describes the steps that developers can take to (1) uncover implicit expertise concerning professional conversations, (2) build a validated conversation model including feasible response options and (3) optimize the play experience so that learners feel sufficiently immersed and engaged while using the simulation-based training. The design process, which is cyclical in nature, is illustrated by means of a case study in which we developed a training for cross-cultural job interviews. Furthermore, we provide practical templates and examples of questions that can be asked to experts and learners during preliminary testing of the scenario. By doing so, we aim to make the process of designing training scenarios more transparent and duplicable, and help developers to avoid pitfalls and tackle conceptual and practical challenges that arise during the design process.