The collection contains 182 holy cards collected by Norman Castle. The cards in this collection address a wide range of devotional subjects including Jesus, Mary, Joseph, the saints, the Holy Spirit, angels, and the sacraments. The majority of the holy cards were mass-produced in France and Germany, with only a few individually produced. Most of holy cards are undated, but the artistic styles employed in the production of the majority of them date from the late nineteenth and early twentieth centuries.

Each holy card is described according to three different criteria: 1. Image description; 2. Text description; and, 3. Language. The primary category of organization of each card is a description of the devotional image on the front, rather than the title of the holy card. The next two categories indicate a description of the text (i.e. prayer, handwritten note, indulgence, explanation) on the back of the card, and the languages used on the holy card, many of which employed multiple languages.