Background: For patients in the ambulatory care clinic setting, an error can occur in any phase of the laboratory testing process, contributing to incorrect or unnecessary medical care, a delay in the continuity and coordination of care, an escalation in legal risk for the organization, and a poor patient experience. Approximately 46-75% of laboratory errors occur in the preanalytical phase of the process, before the specimen reaches the lab. Additionally, the average cost for a specimen labeling error is approximately $712 per specimen. Professional and accrediting organizations, such as the College of American Pathology and The Joint Commission, recommend barcode scanning as a best practice to decrease specimen labeling errors; however, most clinics do not have the software to support barcode scanning. Therefore, non-technological solutions must be explored and implemented. Objective: The purpose of the project was to implement a non-technological practice change to decrease the number of preanalytical specimen labeling errors in clinics at a large academic health system. Methods: A pre-/post-intervention quality improvement design evaluated the implementation of an evidence-based guideline and the use of a double-check verification process. The Clinical and Laboratory Standards Institute (CLSI) GP 33A Guidelines: Accuracy in Patient and Sample Identification recommended practices for patient and specimen identification. Licensed and unlicensed assistive personnel received education through an online learning module followed by a multiple-choice question post-assessment. Five high-volume OB/GYN clinics received onsite training, a pre-/post-multiple-choice written evaluation, and skills validation. Copies of the specimen labeling steps were posted as a cognitive reminder. Results: The hospital occurrence reporting system was reviewed retrospectively over three years to obtain the baseline and the subsequent number of errors classified as requisition/specimen mismatch, unlabeled, and mislabeled. After implementing the CLSI GP 33A guidelines and a two-staff member verification process, 92 labeling errors were avoided that could have resulted in a less-than-optimal patient outcome. The organization experienced a $65,504 potential cost savings. The most common error was unlabeled specimen containers. Five OB/GYN clinics demonstrated sustained improvement with zero errors for more than 365 days. However, the number of unlabeled specimen errors increased when staffing patterns, leadership, and the onboarding process changed during the COVID pandemic. Discussion: Implementing an evidence-based guideline for standardizing the labeling process for specimens collected by the staff created opportunities for education and skill validation. Three improvements contributed to the decrease in labeling errors: 1) accurately identifying the patient, 2) actively engaging patients in the identification of their specimen(s), and 3) using two-staff member’s verification process. Conclusion: Accurate laboratory testing is required for a final diagnosis. Inaccurate laboratory results may lead to a significant delay in medical care, patient dissatisfaction, misdiagnosis, unwarranted invasive procedures, and even death. Recollection of specimens places the organization at increased risk for ligation and impedes continuity of care. Implementing non-technological solutions can be a cost-effective alternative when technology is limited. Replication across the organization is feasible.