Activision has quietly tapped Sledgehammer Games, a Northern California studio, to help out with the making of Call of Duty: Modern Warfare 3, according to people familiar with the situation. The game has not been officially announced by Activision. But the title is well into production and is expected to come out in November, the same month that the publisher has annually released a new Call of Duty installment, people with knowledge of situation said. Modern Warfare 3 will be the first game Infinity Ward has produced since the departure of of company co-founders Jason West and Vince Zampella.

People close to the matter said Infinity Ward is working closely with Sledgehammer, which is led by a team recruited away from Activision's rival Electronic Arts Inc. The two studios are equally sharing duties of producing the single-player portion of the game, the sources said.

Activision has also brought in Wisconsin-based Raven Software, which is working on the online multi-player elements for Modern Warfare 3, sources said.