Tom Ascheim, who headed Viacom’s Nickelodeon TV and Newsweek, has joined ABC Family as president.  He succeeds Michael Riley, who has moved to the U.K.

Ascheim, a financial analyst by training, joined Viacom in 1990 as VP-business development and media products. He rose to the executive VP/GM for Nickelodeon digital TV networks slot before becoming GM of Nickelodeon TV in charge of Nickelodeon, Nick@Nite and Nick Jr.

He exited for the Newsweek helm in 2007 and left three years later with the magazines merger with the Daily Beast.

Sesame Workshop recruited Ascheim for the chief strategy office upped him to the executive VP of Sesame Learning. He left in June following a retrenchment push that led to worker cutbacks.

Former Nickelodeon executive Anne Sweeney is president of the Disney/ABC TV Group and co-chair of Disney Media Networks.

She called Ascheim “an incredibly, smart, strategic executive.”