Is an encyclopedia a primary source?

No, an encyclopedia is a tertiary source. Encyclopedias provide extent information about a particular topic, time period or person in the form of entries arranged in alphabetical order. Encyclopedias, indexes, and works alike are known for compiling primary and secondary sources, as a result, they are considered tertiary sources.

The main characteristic of a tertiary source is that they repackage information, they don’t analyse sources as a secondary source would. Tertiary sources gather, compile and organize information in a specific order, just like an encyclopedia would. Dictionaries and some textbooks are categorized tertiary sources as well when they aim to list information.

Nevertheless, there is always an exception to the rule. Depending on the scope of your research, encyclopedias can be referenced as primary sources. For example, the Encyclopedia Britannica, one of the most popular encyclopedias, was first published in 1768 and is considered a primary source for historians because of the significant value it gained over time.

Britannica 1st ed. Vol.III
Book cover of Encyclopedia Britannica 1st ed., which is considered to be a primary source for historians. Image source: https://commons.wikimedia.org/wiki/File:Britannica_1st_ed.jpg