What Is the Library of Congress Classification System?

The Library of Congress Classification (LCC) is an alphanumeric classification system used primarily by academic and research libraries to organize their collections. Developed between 1899-1920 by the Library of Congress, LCC accommodates very large and specialized collections with greater precision than the Dewey Decimal system.

How Library of Congress Classification Works

The 21 Main Classes

Unlike Dewey’s 10 decimal classes, LCC uses 21 letter-based main classes:

Note: I, O, W, X, and Y are currently unused or reserved for expansion.

The Alphanumeric Structure

LCC call numbers combine letters and numbers for precise classification:

Q - Science
  QA - Mathematics
    QA76 - Computer Science
      QA76.76 - Computer software
        QA76.76.O63 - Operating systems
          QA76.76.O63 L56 2023 - Specific book

LCC Call Number Components

A complete LC call number includes:

1. Class Letter(s)

One or two letters indicating broad subject (e.g., “QA” for Mathematics)

2. Class Number

Whole number indicating subdivision (e.g., “76” for Computer Science within QA)

3. Decimal Extension (optional)

Decimal for further specificity (e.g., “.76” for Software)

4. Cutter Number

Alphanumeric code for author, title, or geographic area:

• First letter represents author’s last name
• Numbers create alphabetical order
• Example: “L56” for “Linux”

5. Additional Elements

• Second Cutter for title (in literature)
• Publication year
• Volume/part numbers
• Edition information

Complete Example:

QA76.76.O63        ← Classification
L56                ← First Cutter (Linux/Torvalds)
2023               ← Publication year

Why Research Libraries Use LCC

1. Specificity

LCC offers far more granular classification than Dewey, essential for:

• Large academic collections (millions of items)
• Specialized research materials
• Interdisciplinary topics
• New and emerging fields

2. Shelf Space Efficiency

The alphanumeric structure allows:

• Better distribution across the alphabet
• Avoiding overcrowding in popular classes
• Room for expansion without major reclassification

3. Designed for Growth

LCC was built to accommodate the Library of Congress’s rapidly growing collection and easily adds new subdivisions.

4. Standard for Higher Education

Most North American research universities use LCC, creating:

• Shared cataloging records
• Familiar system for scholars
• Consistent academic library experience

5. Public Domain

Unlike Dewey (proprietary to OCLC), LCC schedules are freely available and can be modified locally.

LCC in Koha Library System

Configuring LCC in Koha

1. Classification Sources Navigate to Administration → Classification Sources

• Add “Library of Congress Classification” as a classification source
• Set as default if using LCC exclusively

2. Cataloging Frameworks In MARC framework, configure field 050 (LC Classification):

050 _0 $a QA76.76.O63 $b L56 2023

• Indicator 1: Existence in LC (blank=LC assigned, 0=assigned by other agency)
• Indicator 2: Source of call number (0=LC, 4=other)
• $a: Classification number
• $b: Item number (Cutter)

3. Item Call Number (Field 952$o) Combine classification + Cutter for shelving:

QA76.76.O63 L56 2023

Using LCC in Koha Cataloging

When cataloging with LC classification:

Import LC Records via Z39.50:

• Search Library of Congress by ISBN
• Import complete MARC record with 050 field
• Copy classification to item record (952$o)

Original Classification:

• Consult LC Classification Schedules online
• Assign appropriate class and subclass
• Generate Cutter number using LC Cutter tables
• Add to both 050 and item fields

Spine Label Printing

Koha’s label creator handles multi-line LCC call numbers:

QA
76.76
.O63
L56
2023

LCC Resources

Official Resources

• LC Classification Schedules - Full schedules (free PDF downloads)
• LC Catalogers Desktop - Subscription service with search tools
• Classification Web - LC’s official online classification tool (subscription)

Free Tools

• LC Online Catalog - Search to find LC call numbers for specific titles
• OCLC Classify - Find consensus call numbers by ISBN/OCLC number
• LC Cutter Tables - Freely available for generating author/title Cutters

In Koha

• Z39.50 import from Library of Congress
• LC number lookup plugins
• Classification browser tools

Common LCC Cataloging Challenges

1. Complexity

LCC has steeper learning curve than Dewey:

• More classes to memorize
• Complex Cutter table rules
• Irregular organization in some classes

Solution: Rely heavily on imported records; use Classification Web for original cataloging.

2. Inconsistent Organization

Unlike Dewey’s pure decimal logic, LCC evolved pragmatically:

• Similar topics may be scattered (e.g., computer science in QA, T, Z)
• Some classes more developed than others
• Historical biases reflect early 20th-century worldview

Solution: Use LC schedules and manuals; don’t assume logical consistency.

3. Keeping Current

LC continuously updates schedules with new numbers and relocations.

Solution: Use LC’s online schedules; subscribe to updates; don’t reclassify retrospectively unless necessary.

4. Local Variations

Many libraries modify LCC for local needs:

• Expanding local/regional history
• Creating special collections
• Keeping older numbers when LC relocates topics

Solution: Document all local practices; maintain authority file of local decisions.

LCC vs. Dewey Decimal Classification

Practical Tips for LCC in Koha

1. Import Professional Records - Use Z39.50 to get LC-assigned call numbers
2. Use OCLC Classify - Find consensus LC numbers for materials not in LC catalog
3. Master Cutter Tables - Essential skill for consistent call numbers
4. Document Local Practices - Create internal manual for local variations
5. Train Thoroughly - LCC requires more training than Dewey
6. Use Classification Web - Worth the subscription for original cataloging
7. Be Consistent - Maintain shelf list of assigned numbers

Example LCC Numbers by Subject

• BF76 - Psychology (general)
• E185.61 - African American civil rights
• F594 - History of Texas
• HD9999.C94 - Computer software industry
• ML410.B4 - Biography of Beethoven
• PN1997.2 - Individual motion pictures
• PR6068.O93 - J.K. Rowling’s works
• QA76.73.P98 - Python programming language
• RC569.5.I54 - Internet addiction
• Z711 - Library administration

Transitioning from Dewey to LCC

Some academic libraries transition from DDC to LCC as they grow. Considerations:

Pros of Switching:

• Greater specificity for research collections
• Alignment with peer institutions
• No licensing costs
• Better academic library standard

Cons of Switching:

• Massive reclassification project
• Staff retraining required
• Patron confusion during transition
• Loss of Dewey’s browsing logic

Hybrid Approach:

• Keep existing Dewey collection
• Use LCC for all new acquisitions
• Gradually reclassify high-use items
• Complete transition over 5-10 years

Conclusion

Library of Congress Classification is the classification system of choice for academic and research libraries managing large, specialized collections. While more complex than Dewey Decimal, LCC provides the specificity and flexibility needed for scholarly materials.

Koha fully supports LCC through proper MARC handling, integration with Library of Congress records via Z39.50, and configurable call number management. Libraries using or transitioning to LCC will find Koha’s tools robust and flexible.

Whether you’re an academic library using LCC from the start or considering a transition from Dewey, understanding LCC principles and best practices is essential for effective collection organization and patron access.

Need help implementing or migrating to Library of Congress Classification in Koha? Our team provides classification consulting and migration services. Contact us to learn more.