The delay analysis practice spreads around the world. The cost engineering community address the fact that the underlying concepts for delay analysis is insufficiently established. Many of the techniques currently applied lack a sound theoretical basis. This presentation on Measurement of Delay and Theory and Application expands on a paper published at the AACE International 2020 Conference and Expo. That paper directly addresses the question “What is Delay?”. It establishes fundamental principles for the measurement of delay. Those principles presents to explain why popular delay analysis techniques fail by neglecting to apply the scientific method. The correct approach explains in this course on Measurement of Delay and Theory and Application.