Over the years, many authors have tried to describe, conceptualize, and visualize the instructional design or development processes via a variety of process models. Most descriptions imply a rather homogeneous view of design, depicting it as an overall problem-solving process following general phases such as analysis, design and development, implementation, and evaluation (ADDIE). However, researchers who have investigated how instructional designers actually work suggest that the process is much more heterogeneous and diverse than these ADDIE models suggest. This study collected case study data from 24 instructional designers in six different settings; they were identified as experts by their peers. The design processes they used for a specific project were compared to four different paradigms created from the literature. The four paradigms and their underlying theoretical foundations are described and illustrated. Detailed results are reported, and reasons that designers did or did not use a particular paradigm are considered.