The relationship between project selection and requirements analysis is important, yet has not received much attention. The decisions made during project selection directly affect and frame a project's requirements analysis. In current practice, it is expected that requirements analysis begins after project selection has occurred. Yet, we know little empirically about the procedural relationship between project selection and requirements analysis. We performed a field study to examine in detail how project selection is performed and what procedural relationship, if any, exists between project selection and requirements analysis. We found, contrary to the common view of requirements engineering practice, that requirements analysis occurred in multiple parallel streams. We observed that requirements analysis helped define the initial project choices. In addition, as the project selection process progressed, each candidate project's requirements were further refined. We call th...