Langer carded a 5-under-par 67 at La Vallee du Richelieu Golf Club's Rouville Course, ending 36 holes at 6-under 138.
That's three better than Charles Schwab Cup points leader Kenny Perry (71), Willie Wood (68), Chien Soon Lu (68), Bill Glasson (69) and Anders Forsbrand (69), all at 3-under 141.
Langer grabbed the lead after Duffy Waldorf bogeyed the 12th and took off from there.
Sharing seventh place at 142 were Waldorf (70), Michael Allen (68) and Esteban Toledo (69).
First-round leader Dick Mast had a tough go of it Saturday, registering a 75 to end in a tie for 17th place.