While Communicative Language Teaching (CLT) is nowadays widely recognized, the implementation of CLT in foreign language (FL) classrooms remains difficult. In the Netherlands, communicative learning goals have been formulated at the national level, but in daily practice assessments and learning activities tend to focus on knowledge of grammar rules and vocabulary out of context. Under the principle of constructive alignment, assessment and learning activities should be in line with learning objectives in order to enable effective teaching. Evaluation in particular plays a key role, because it has a direct impact on teachers' pedagogical choices and students' learning behavior (i.e., washback effect). To enhance alignment in the Dutch FL curricula of lower form education, the first author and 21 FL teachers collaborated to create a realistic, theoretically grounded communicative assessment program that would enable positive washback. This paper takes inventory of the challenges faced by teachers during the co-design process and the decisions that have been made to overcome them.