In this paper I argue that Ancient Greek has two distinct strategies for relative clause formation, corresponding to what is known in typology as externally and internally headed relative clauses. Furthermore, I explore two differences between these constructions. First, in comparison with their external counterparts, internal constructions are more restricted semantically. They can only be interpreted as restrictive relative clauses, while external constructions can also be interpreted as non-restrictive. Second, internal constructions are more restricted syntactically, given that they are not used when the domain nominal is subject in the relative clause. For external constructions there is no such syntactic restriction. Finally, I point out a number of convergences between internal relative clauses and noun phrases with an attributive participle. The findings presented in this paper are based on a study of Xenophon.