The Computer Systems Research Group (CSRG) was a research group at the University of California, Berkeley that was dedicated to enhancing AT&T Unix operating system and funded by Defense Advanced Research Projects Agency.

The group had licensed the source code from AT&T early in the 1970s, but as the operating system became very popular, AT&T jacked up the licensing fee. This became very controversal, and the computer systems research group set up a goal for themself to replace all the source code that originated from AT&T.

The group works went by the name BSD, and the last release from the group was called 4.4BSD-lite. The group was disbanded after it lost financing. It is sometime suspected that the loss of the financing could have something to do with AT&T, as the two organizations were not in good terms at that point.

Noted former members of the CSRG include Bill Joy and Marshall Kirk McKusick.

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