Infrastructure and operations (I&O) professionals are adopting the disciplines of modern service delivery to deliver modern applications and services with the speed, quality, and agility that customers demand. To support the continuous improvement of modern applications and modern services throughout their life cycles, I&O leaders should adopt Deming's plan-do-check-act (PDCA) model to build and test improvements to processes. This report describes how I&O professionals can deploy the PDCA cycle to improve the quality and speed of service delivery. This is an update of a previously published report; Forrester reviews and updates it periodically for continued relevance and accuracy; we revised this edition to factor in new ideas and data.