Classical Trinitarian Theology is a textbook on patristic Trinitarian doctrines constructed in three parts. Part I introduces classical Trinitarian theology with the help of short discussion, definitions, and comparisons. It is designed for incoming seminary students, who have never formally studied theology. Part II is for intermediate students. It comments on three charts, which attempt to depict graphically the patristic search for Christian Trinitarian theology. This section is geared towards seminary students who have already studied for a few years and would like to revisit the classical doctrine of the Trinity at a more advanced level, but who are not really ready for engaging primary texts independently, whether in Greek, Latin, or English. Part III is composed for advanced students who enjoy tackling primary texts. It provides a list of some important Greek or Latin primary texts and the accessible translations in English.