A concept inventory (CI) instrument allows instructors to measure student misconceptions and address them in a course. The instrument is typically a multiple-choice question test designed to assess the understanding of concepts by a student. The questions focus on reasoning and logic rather than on declarative knowledge of the subject matter. In this paper, we chronicle the development of a concept inventory in Numerical Methods for Engineers as part of a current NSF TUES grant. We focus on the timeline so that readers can themselves follow the intricate process of developing a concept inventory - identifying concepts through experts using DELPHI technique, developing questions, assessing individual questions, and testing for reliability and validity.