Google Inc. is working on plans to start a venture-capital arm, according to several people briefed on the discussions.

The group will be led by David Drummond, Google's senior vice president of corporate development and chief legal officer, according to two of these people. Google has hired William Maris, a 33-year-old former entrepreneur who has worked as an investor, to help set up the venture. How the group will be structured and what sort of investments it is likely to target remain unclear.

Google...