Roger Sterling is a Partner at the Sterling Cooper Draper Pryce advertising agency; his father founded the original Sterling Cooper in the 1920s with Bertram Cooper. A World War II veteran, Roger has suffered two heart attacks. In the past he's tried to change his hard-living ways, but is now smoking and drinking again.
Roger divorces his first wife, Mona, after taking up with the much younger Jane Siegel, who briefly worked as Don Draper's secretary. Previously, Roger had a lengthy affair with Joan Holloway, then Sterling Cooper's Office Manager.
Anticipating a costly divorce settlement with Mona, Roger encourages the takeover of Sterling Cooper by London's Puttnam, Powell, and Lowe. When the new managers leave him off a corporate organizational chart, however, Roger believes he's "being punished for making my job look easy." He feels similarly slighted by friends who can't accept his relationship with Jane. "I made a mistake by being conspicuously happy," he tells Don.