This preliminary study explores the concept and practice of prayer found in the writings of six major Stoic philosophers from the ancient world: Zeno, Cleanthes, Chrysippus, Seneca, Epictetus, and Marcus Aurelius. Placing these writers in their context within the evolution of Stoic philosophy, and in their socio-religious and historical context, McDowell then characterizes the nature, purpose, and practices of Stoic prayer. A brief comparison with prayer from the New Testament closes the study.