There was no word yet on whether the team was pursuing outfielder Carl Crawford, although that would appear to be a no-brainer.
This is all very early in the process, and the Beltre and Werth negotiations are expected to be protracted.
Werth has blossomed in his four seasons with the Phillies after four so-so years with the Blue Jays and Dodgers. The .272 lifetime hitter has batted .282 while averaging 24 homers and 75 RBIs per season in Philly. He is coming off a four-year deal that paid him $7.5 million last season.
The Red Sox went into last season with Mike Cameron, Jacoby Ellsbury and J.D. Drew in the outfield, but injuries derailed that lineup. Cameron was limited to 48 games with an abdominal injury that required surgery, and Ellsbury played in only 18 after breaking ribs.
Cameron and Drew are under contract for next season, and Ellsbury is arbitration eligible.
Gordon Edes covers the Red Sox for ESPNBoston.com.