This study exposes shortcomings of arguments that view an “open ending” theory of Mark as a modern construct that would have made little sense to an ancient audience. It looks at 1st century genre expectations in light of cognitive genre theory and argues that a reader-response approach to Mark’s ending is not only appropriate but also desirable. First, it describes and assesses interpretative issues surrounding Mark’s ending. Second, it discusses ways of approaching Mark’s ending in light of genre expectations, building on a literary approach to genre with a cognitive (psychological) approach. Third, it offers an interpretation of Mark’s ending in light of its fit with Greco-Roman bios and in terms of cognitive models. It shows how Mark develops a pattern of imitation between Jesus and his disciples that, at the end, invites the audience to reflect on and respond to the person of Jesus and his role as the exemplar of discipleship.