The parasitoid complexes of tortricoid (Lepidoptera: Tortricoidea) hosts were investigated to determine the component parasitoid guilds, the utilization of these guilds, and the host ranges of the parasitoid taxa. This provided an alternative, mOt;e detailed perspective on the structure of parasitoid complexes than the approach pioneered by Askew&Shaw (1986). The component parasitoid guilds are defined by three parameters: the host stage attacked, the mode of parasitism (ecto- or endoparasitism), and the form of parasitoid development (continuous or protracted). Characteristics of the 11 guilds of parasitoids of tortricoid hosts are presented in detail. Tortricoid hosts support a parasitoid complex of ≍9 species, with notable similarity in the utilization of parasitoid guilds in both the Nearctic and Palearctic regions. The complexes are dominated by koinobiont larval endoparasitoids and idiobiont pupal parasitoids. The host range of tortricoid parasitoids show some broad support for Askew&Shaw's (1986) hypothesis that parasitoid lifestyle can be used as a practical indicator of the breadth of the host ranges of parasitoids. However, the extent of exceptions indicate that the hypothesis cannot be accepted for parasitoid complexes in general and point to the importance of both parasitoid taxon and the host stadium attacked in influencing parasitoid host ranges. The relative merits of parasitoid guilds and parasitoid lifestyles as concepts in the analysis of parasitoid complexes are discussed.