In 2011, a team of teachers in Luxembourg developed a proposal to reform their national English language examinations. The teachers sought advice from external language testing consultants and expressed a wish not only to transform their existing examinations, but also to develop their own capacity to construct and evaluate language assessments in line with the principles of good test design. What transpired was a unique, phased language assessment literacy training-development cycle which has led to the successful development of a lower-stakes national test, and the planning stage for a high-stakes end-of-secondary school exam – the key objective of the project. In this chapter we will provide a narrative account of the reform project in Luxembourg, presenting this context as an illustrative case of teacher-led exam reform in a high-stakes context, and discussing the procedures and challenges encountered between 2011 and 2015. Based on our experiences as consultants on this project, we make some recommendations at the end of the chapter for those working with a similar remit for training and advising on teacher-led exam reform.