This thesis aims to contribute to the study of divine providence in relation to the entry of sin into the world via a constructive metaphysical enquiry, seeking to deepen our reading of the work of Thomas Aquinas. Popular accounts of providence over sin are inadequate to Holy Scripture’s dual affirmation of the agency of both God and creatures. Aquinas’ work transcends the common pitfall of contrastive conceptions of these two agencies, but is underappreciated both on the level of lay-thought and in scholarly treatments on the doctrine of providence. Attention to the several parts of Aquinas’ work are salutary for the doctrine of providence, including the doctrines of divine simplicity and the divine will, and how these relate to the doctrine of creation as its guiding principles. The metaphysical vision of creation as participation in God makes way for providence as creatio continuata, wherein divine and human agency are not contrasted but conceived of in right order. When creatures are treated of not as primary, but always in reference to the simple will of God, two things follow. Firstly, earlier logical problems implicit in typical renderings of providence or the “problem of evil” become void. Secondly, the Thomistic adaptation of Aristotle’s fourfold causality makes it necessary to consider even evil things (failures of participation) in reference to the divine will and divine goodness. The result of this study is to envision God’s permission of sin as something conducive of God’s will for His own goodness. The thesis concludes by claiming that the Thomistic vision of God and creation is fitting in light of what Holy Scripture teaches. Through advancing our reading of Aquinas’ work, I argue that the divine will is the central structure for understanding the relationship of sin to God’s providence over the created order.