This volume contains a survey of 51 ring systems in which an imidazole ring is fused to an additional five-membered ring system. Ring systems included are those appearing in the Chemical Abstracts Index of Ring Systems under the 2-ring 5-5 citation and including a C3N2 fragment. The material is subsequently subdivided into chapters based on the number and types of hetero atoms in the additional 5-membered ring. The synthesis, physiochemical properties and reactions of compounds in each ring system are covered; reactions are organized on a mechanistic basis and the survey includes compounds that are both partially and fully saturated.