The diversity of the religious systems in Roman and Latin colonies of the Middle Republic indicates that Roman expansion into Italy was not a unilateral, purely hegemonic phenomenon, but a complex interchange of cultural ideas between Romans, colonists, and locals. My dissertation examines the development of the cults in colonies founded in Samnium, Campania, and Northern Italy between 338 and 177 BCE. Through analysis of the composition and duties of the three-man colonial commission, the religious landscape of the colonies, and the broad cultic trends in these regions, I establish that religion in the colonies reflected the experience of the individuals who founded them and the needs of the individuals who inhabited them. The three-man colonial commissioners, the tresviri coloniae deducendae, used their experience as generals, magistrates, and priests to lead the colonists to their new home, organize the space, and define the institutions. The factional divisions and personal ambitions of the commissioners drove the composition of the commissions and, thus, the form and institutions of the colonies founded. Through the differences of intention and colonial strategy held by the commissioners, the colonies did not espouse a codified Roman settlement pattern, but instead the political and cultural principles of their founders. The religious life of each settlement developed beyond its initial foundation by means of the interactions of the colonists and local populations. Through a new model of colonial foundation which combines the human factors of Roman colonization: commissioners, colonists, and locals, with their impact on, and interaction with, the colonial landscape, I demonstrate that the religious landscape of the colonies of Fregellae, Paestum, and Sora did not mirror that of Rome, but reflected the religious and spatial needs of the colonists. Finally, the evidence for the cults of Juno, Diana, Minerva, Hercules, Mars, and Jupiter in Central and Northern Italy shows that the colonists participated in many religious systems: some cults honored Roman versions of the gods, but more honored local, Latin, or even Mediterranean conceptions of a deity. Thus, these cults drew the colonists together with the locals in a shared religious tradition familiar to both groups.