The ISPE APQ Guide: Corrective Action and Preventive Action (CAPA) System is the first in the planned four-part series that seeks to improve the state of pharmaceutical quality and ensure sustainable compliance. The Guide Series is part of ISPE's newest initiative, Advancing Pharmaceutical Quality (APQ), a comprehensive program for assessing and improving an organization's quality management maturity. Built upon the ICH Q10 Pharmaceutical Quality System (PQS) model, the APQ program is an industry-led approach that seeks to advance pharmaceutical quality beyond the submission of data for harmonized, reportable metrics. The program is aligned with international initiatives that promote quality excellence, as well as with the FDA's interest in quality management maturity and rating the maturity of manufacturing facilities, as cited in their 2019 Drug Shortages report. The result is a program that organizations can leverage to ensure a continuous supply of quality medicines to patients.