Theoretical sampling is a hallmark of grounded theory methodology, and yet there is little guidance available for researchers on how to implement this process. A review of recently published grounded theory studies in Qualitative Health Research revealed that researchers often indicate that they use theoretical sampling to choose new participants, to modify interview guides, or to add data sources as a study progresses, but few describe how theoretical sampling is implemented in response to emergent findings. In this article, two issues that arose relative to theoretical sampling in an ongoing grounded theory study are discussed. A theoretical sampling guide that was developed by the authors' research team to facilitate systematic decision making and to enhance the audit trail relative to theoretical sampling is described, and an example of how the guide was used to develop a category is presented.