Preface : I have tried to investigate in this book, the relationship between Bhojpuri and Bengali. Since Bhojpuri and Bengali are the descendants of the same source, Magadhi Prakrit, their comparative study is significant. The speeches originating from Magadhi Prakrit have been classified into three Groups : 1. Eastern Magadhan - Bengali, Assamese, Oriya 2. Central Magadhan - Maithili, Magahi 3. Western Magadhan - Bhojpuri with Nagpuri or Sadani Whereas Bengali is the language spoken by the largest number of people in the Indian subcontinent, being spoken in Bangladesh as well as West Bengal, Bhojpuri is a dialect spoken in a widespread area spread over Eastern Uttar Pradesh and Western Bihar. While the Bhojpuri area is closely related to Uttar Pradesh in terms of society and culture, it has close affinity with Bengal in terms of language. But there has been no consciousness among the people of Bengal and Bihar that their language has originated from the same source. On the contrary, Bihar is considered today to be a part of the so-called Hindi-belt. The book has been divided into ten chapters. The first chapter gives an introduction of both the speeches, their origin and mutual relationship and the purpose of comparing them. The second and third chapters give the comparative study of the phonology of the two speeches. Chapter III to IX deal with the morphology of the two speeches, i.e., the nominal declension, the pronoun, the numeral, the verb, the prefix, the indeclinable and the suffix. E.g., in phonology, a major point of similarity between Bhojpuri and Bengali is the rounded pronunciation of (a). Grammatical gender has been preserved in all New Indo-Aryan speeches except the Magadhan speeches. In Bhojpuri, the gender has been partially preserved. In Bengali, the gender distinction is totally lost. Regarding verb, both in Bhojpuri and Bengali-l- is used for the past base and -b- for the future base.