Developing a strong assessment system is a priority for many countries. But where should they start? This paper describes the journey experienced by Chile to develop the enabling context (policies, institutions, and human and fiscal resources) for its large scale assessment program, its university entrance examinations, and classroom assessment activities. Countries aiming to develop their assessment system may draw valuable lessons from this case study, most importantly the following: (i) developing the right enabling context is a long term process that builds on gradual changes; (ii) stakeholders should be represented in the governance of the assessment unit; (iii) while different institutional arrangements are possible for an assessment unit, it is important that the unit is accountable and autonomous to make technical decisions; (iv) countries need to develop local capacity in assessment; and (v) countries need to anticipate the pressure the expansion of the education system will put in the assessment system, especially in the university entrance examinations. Countries that can benefit from these lessons will be in a better position to continue on the journey of strengthening their enabling context for an effective assessment system.