Glencairn Museum holds several other collections that have not been allotted gallery space, but are used decoratively throughout the building or appear in special exhibits. A selection of these special collections follows below.

Raymond Pitcairn collected antique furniture in the process of furnishing Glencairn as a home. The collection is mostly European, consisting primarily of Windsor chairs, tables and storage chests. Several pieces of ecclesiastical furniture are of special interest, and the Museum has received several pieces of religious significance through donors. The photo above shows a carved figure of a monk reading, and is part of a three-seat choir stall from 15th or early 16th century Spain. Stalls like these were used as seating for monks in a church, and this example is elaborately carved with Christian symbolism.

The Museum's collection of oriental rugs was acquired by Raymond Pitcairn. The emphasis of the collection, numbering over 200 pieces, is on village and tribal rugs, including a number of prayer rugs. The decoration of prayer rugs is rich in Islamic symbolism, even including symbols from religions that existed in the ancient Near East before Islam. The "mihrab," apparent in the example above, is an arch that points toward the Holy City of Mecca. Both the rug and the worshipper praying on it were required to point toward the Holy City. In Islamic tradition this arch represents the "gateway to paradise." However, the symbol of an arch as a gateway to paradise has its origin in ancient Mesopotamian symbolism, which predates Islam by several millenia.

The Raymond and Mildred Pitcairn Archives contain written materials, photographs, and memorabilia from the lives of Raymond and Mildred Pitcairn. The Pitcairns built Glencairn from 1928 to 1939, and lived in it as their home for the remainder of their lives. A gallery on the fifth floor, next to the chapel, is devoted to the Pitcairn family. This gallery includes family memorabilia and notebooks of various ongoing Archives projects. These projects include an oral history project, and a collection of sources about the craftsmen who made Bryn Athyn Cathedral and Glencairn.

The main collections of the Archives are housed in a separate storage area in Glencairn. The highlight of the Archives is the material relating to the building of Bryn Athyn Cathedral, including a large collection of photographs and architectural drawings from the construction of the Cathedral as well as Glencairn. There are also many business papers, employee records, correspondence, and other written documentation. One of the most interesting pieces is Raymond Pitcairn’s unpublished manuscript on the history of the Cathedral’s construction.

Another large collection consists of United States political material from the 1920s through the 1960s. Raymond Pitcairn was very involved with conservative political causes and candidates. The Pitcairns came to know Dwight and Mamie Eisenhower through their political activities, and there is a collection of correspondence between the two couples.

The Archives also houses a collection of family memorabilia including letters, school papers, housekeeping notes, and a few textiles and larger objects. There are also various materials from the Pitcairn’s involvement with the General Church of the New Jerusalem and the Academy of the New Church. The large photograph archive includes a collection of over 4000 glass plate negatives from the early twentieth century.