This thesis examines the sanctuaries of the Greek goddess Demeter in Western Asia Minor and on the islands off the coast through a comparative approach that analyses archaeological and written sources across time and space. The research encompasses the region on Western Asia Minor that includes Troas, Aeolis, Ionia, Caria and the islands off the coast, from the Late Archaic to Roman periods. The analyses focuses on the architectural features of the shrines, the iconography of the dedicated votives and the epigraphic evidence for the cults of Demeter, Persephone and Hades. Cultic activities are analysed on the basis of archaeological material and written sources. The comparative methodology employed aims to analyse the architectural features of the shrines of Demeter in Western Asia Minor and on the islands off the coast in comparison to mainland Greece and in Magna Graecia (including Sicily) in order to assess Pan-Hellenic and regional characteristics. Such an analysis is made for the first time in this thesis, building on similar analyses recently performed for other areas. A better understanding of the social context associated with the cultic activities performed at the shrines of Demeter in Western Asia Minor and on the islands off the coast is achieved through the analysis of the iconography of the clay votives dedicated at the shrines in connection with the epigraphic evidence, which provides insight into the social background of those worshippers who performed certain cultic activities, and evidence of festivals and polis involvement in the organisation of cultic activities. Considering in parallel the result obtained from these three types of evidence (architectural, iconographic and epigraphic) significantly deepens potential understanding and future research questions concerning the cult of Demeter in Western Asia Minor and on the islands off the coast.