Unlike common keyword searches, which are based on exact word matches, subject or thesaurus searches retrieve records based on assigned subject headings or descriptors.

Subject headings, descriptors, and thesauri terms are examples of controlled vocabularies--pre-defined, carefully selected words and phrases used to classify and organize information. Controlled vocabulary describes the overall content of an information unit, such as a book, article, or essay. Searching with controlled vocabulary in a subject index or thesaurus allows for more precise results, reveals relationships between related terms, and helps identify synonyms as well s broader and narrower terms.

Subject headings and thesauri terms vary by discipline and database. For example, ATLA Religion database includes a Scripture search, while APA PsycInfo uses the APA Thesaurus of Psychological Index Terms.

Keyword and subject terms searching can be combined. For example, rather than guessing what keywords to use consider doing a thesaurus (controlled vocabulary) search first. Review and assess your results. Then, add a keyword search to the query or use Search History to combine searches.

Identify all the major concepts of your thesis or research topic. Then use the thesaurus or subject index to locate, explore and select subjects (also known as descriptors) for each concept of your topic.

For an ATLA Subject Thesaurus search:

1. In Advanced search, click Subjects and enter a term like Great Awakening in the Humanities Thesaurus search box.
2. Choose a display option (e.g., Relevancy Ranked or Term Contains) then search.
3. Click the term to view the scope note and related subjects, as shown in the example below.
   Or mark the box(es) next to your desired term(s) and click Add to search to insert the subjects into the search boxes.

America: History and Life with Full Text offers access to 168 exclusive full-text journals, indexes 1,318 active journals (including 1,186 peer-reviewed), and includes a time period search feature alongside standard search options.

For a thesaurus or subject search:

1. In Advanced search, click Subjects and enter a term like Great Awakening in the Humanities Thesaurus search box.
2. Choose a display option (e.g., Relevancy Ranked or Term Contains) then search.
3. Click the term to view the scope note and related subjects, or mark the box(es) next to your desired term(s) and click Add to search to insert the subjects into the search boxes.