Attention deficit/hyperactivity disorder (ADHD) is a chronic disorder that afflicts individuals into adulthood. The field continues to refine diagnostic standards for ADHD in adults, complicated by the disorder’s heterogeneous presentation, subjective symptoms, and overlap with other disorders. Two key diagnostic questions are from whom to collect diagnostic information and which symptoms should be contained on an adult diagnostic checklist. Using a trifactor model, Martel et al. examine these questions in a sample of adults with and without self-identified ADHD symptoms. In this response, we highlight the importance of their finding that self and informant symptom reports differ in a sample of adults who acknowledge ADHD symptoms. We also review issues that continue to face the field related to model specification, evaluating symptom utility, and sample composition, discussing how these issues influence conclusions that may be drawn from Martel et al. and similar investigations. We conclude that the article makes an important research contribution about the nature of self and informant ADHD symptom reports but emphasize that symptom checklist refinement must occur through a broad lens that considers work from a range of sample types and clinically informative analytic strategies.