- Kant, Immanuel
- Kautsky, Karl
- Kelly, George Alexander
- Kerr–Siegel hypothesis
- Keynesian economics
- kibbutzim
- kinesics
- Kinsey, Alfred
- kinship
- Kish grid
- Klein, Melanie
- Klein, Viola
- Kluckhohn, Clyde
- knowledge, sociology of
- Kollontai, Alexandra
- Kondratieff cycles
- Kroeber, Alfred Lewis
- Kuhn, Manford
- kula ring
- Kuznets cycle
