Context.-Previous studies have shown that there are disagreements in interlaboratory consultation, including false-negative and false-positive diagnoses. To date, methods to reduce false-negative and false-positive diagnoses have been poorly documented. Objective.-To identify features associated with false-negative and false-positive diagnoses in anatomic pathology. Design.-We reviewed the results of interlaboratory consultation in our institution during a 9-year period. For false-negative and false-positive diagnoses, methods that might have prevented the error were identified. Results.-Disagreements were identified in 810 of 8082 consults (10%). Fifty-four false-negative cases (0.7% of all consults) and 27 false-positive cases (0.3%) were identified. False-negative cases were more common in breast (20 of 1131; 1.8%), genitourinary (16 of 970; 1.7%), hematologic (3 of 242; 1.3%), and cytology (3 of 404; 0.8%) than in all other sites combined (P < .001); no significant difference in sites were identified for false-positive cases. Overall, there was no difference in the percentage of cases that were reviewed by more than one pathologist in either false-negative cases (109 of 810; 13.5%) or false-positive cases (135 of 810; 16.7%), compared with all other consults (858 of 7272; 11.8%) (P = .74 and .59, respectively). However, on review, 12 of all 27 false-positive cases (44%) might have been prevented by the use of immunohistochemistry alone, and 36 of all 54 false-negative cases (67%) might have been prevented by the use of a second review; special stains, including immunohistochemistry; additional levels; changes in processing; and hedges. Conclusion.-Approximately one-half of false-negative and false-positive cases (48 of 81; 59%) might be preventable by the use of a combination of pathologic methods.