While When the Tripods Came is an adventure story and, at times, does not fully develop its characters, it goes beyond mere formula. It develops a number of important themes, primarily through a credible narrator who is both opinionated and introspective. At the same time, it creates and then undermines apparent stereotypes, particularly in its depiction of Laurie's grandmother and stepmother. Christopher's narrative is direct, suspenseful, and continues to build throughout the novel. As Zena Sutherland has noted, the book will keep readers reading and is a worthy addition to the other volumes in the series.