Despite scholars’ ongoing historical and sociological investigations into the ancient family, the right and the status of the firstborn son have been rarely explored by NT scholars, and this topic has not attracted the careful attention that it deserves. This work offers a study of the meaning of the firstborn son in the New Testament paying specific attention to the concept of primogeniture in the Old Testament and Jewish literature. This study argues that primogeniture was a unique institution in Jewish society, and that the title of the firstborn son indicates his access to the promise of Israel, and is associated with the right of the inheritance (i.e., primogeniture) including the Land and the special status of Israel.