Technical Abstract: This selective review of 40 years of coccidiosis research is one of a number being written on important diseases of poultry to celebrate the 40th anniversary of the birth of Avian Pathology, the journal of the World Veterinary Poultry Association, and is written for the non-specialist. Our intention is to provide a flavour of the field problems and intellectual challenges, with an emphasis in the areas of immunology and vaccinology, that drove research in the 1970’s and to reflect on research progress since. The 1970’s sit in the middle of the modern history of 80 years of research in to avian coccidia. The decade now looks (1) backwards to the pioneering work on coccidia and coccidiosis in the late 1920’s and early 1930’s by researchers who laid the foundations of much fundamental knowledge, including speciation, life cycles, pathogenicity, host-specificity, induction of protective immunity and control by vaccination and chemotherapy and (2) forwards to the modern era in which molecular approaches are being applied to many studies, including Eimeria genomes and genetics, immune mechanisms and protective antigens and host susceptibility with the real prospect that a new generation of innovative vaccines will emerge. In this short and very highly selective review, the reader will be referred to many of the substantive texts and references to primary data for more detailed information. This review is also mostly written from our personal perspectives so that we can best give insights in to how some of the scientific questions of the day were framed and addressed. We therefore apologize to very many colleagues and other coccidiologists whose names and work are either not described at all or only in passing. In particular, whilst the absolutely critical importance of chemotherapy to the control of coccidiosis is highlighted, less attention is given to this topic in our descriptions of scientific progress.