Study of diagnostic practice is necessary to optimize neurologists' clinical performance and ensure patient safety. To our knowledge, this report is the first set of systematic observations of diagnostic practices of community neurologists in their clinics. The study consisted of six 2-week periods of in situ observations and interviews of 6 experienced community neurologists in Northern California. We describe 3 core domains of diagnosis: 1) clinical (C), 2) laboratory and electrodiagnostics (L), and 3) neuroimaging (N). Neurologists were uniform in their practices across these domains except within the clinical domain, where the physical examination varied considerably among clinicians. All neurologists coordinated findings from the 3 domains to arrive at a final diagnosis. This practice of coordination varied across common disease categories (e.g., meningitis vs dementia). To codify this variance, we developed a provisional model of diagnostic practice derived from the data consisting of a 3-point coordinate shorthand (Cx Lx Nx) and a graphic. This model shows the relative emphasis of each of the 3 core domains for 9 common diagnoses (e.g., stroke is C4 L1 N4 with "4" as the highest priority per domain). The data reveal a heavy emphasis on the clinical domain for most diagnoses. The model may be useful for trainees to learn how to allocate time to make a diagnosis. It may help educators build curricula and evaluation systems that emphasize concrete activities of diagnostic practice. Lastly, our model provides a structure to teach resource utilization and cost containment relating to neurologic diagnoses.