Marc Teren, chief executive of The Washington Post Co.'s Internet subsidiary, resigned yesterday after three years at the helm to take a senior position with another publishing venture. He was replaced by his second-in-command, Christopher M. Schroeder.

Teren, a former Walt Disney Co. executive, oversaw the development of washingtonpost.com into the nation's third most frequently visited online newspaper site and was a driving force behind the recent news-sharing alliance with MSNBC.com.

At the same time, Teren pushed with mixed results for a competing strategy that sought to appeal to an Internet audience beyond the traditional Post readership by offering an online gateway to community news and information, weather, and traffic reports.

That internal debate was not a factor in his leaving, according to Post officials and Teren's associates, but it highlights a challenge facing The Washington Post and other newspapers as their competition with Internet rivals intensifies, industry analysts said.

Schroeder, 35, succeeds Teren as chief executive and publisher of Washingtonpost.Newsweek Interactive (WPNI), which operates washingtonpost.com and Newsweek.com. A former partner with Thayer Capital Partners, a Washington-based investment company, Schroeder headed The Post company's Legi-Slate Inc. subsidiary, which was sold in June 1999, before joining WPNI. He also worked in George Bush's 1988 and 1992 presidential campaigns and in the State Department during the Bush administration.

Schroeder said The Post's online newspaper remains its first priority, but it will continue to develop onwashington.com, the local "portal" launched under Teren in November, which has developed slowly since then.

Washingtonpost.com and onwashington.com averaged 74 million visits, or "page views," per month from July to November 1999, a 15 percent increase from the same period in 1998, but the company did not say how much of that traffic was due to onwashington.com.

Schroeder called the new site "a work in progress" and said: "We're assessing the best ways to progress. We're in a very different medium [than the newspaper], and we have to look creatively at it."

"It's a very complex thing to create a new, independent, interdependent Internet company at a very old-guard, old-line company like The Post," said industry analyst Peter M. Zollman, a WPNI consultant.

The issues go beyond the role of news in online sites, including questions of whether newspapers and their online ventures compete for local advertisers or share them.

The Post has augmented its site by adding a PM Extra edition, with staff-written breaking news and columns that appear every weekday at 1 p.m. It also runs video clips from MSNBC. Meanwhile, Post and Newsweek articles are carried by MSNBC.com and the two organizations' reporters have appeared on MSNBC cable broadcasts.

CAPTION: Christopher M. Schroeder becomes chief executive of The Post's Internet subsidiary.