In this chapter we take a closer look at parties’ replies and comments. Parties’ replies and comments are governed by general principles of procedural law and a network of co-operational duties, both in their horizontal and vertical dimension. Is there an (un) limited freedom(not) to reply? Does it matter who is replying? Does the quality of replies call for any comment? How do oral and written replies relate? What is the functional role of documents in replies and comments?