Methods for controlling lost circulation in subterranean wells, and in particular, fluid compositions and methods for operations during which the fluid compositions are pumped into a wellbore, enter voids in the subterranean-well formation through which wellbore fluids escape, and form a seal that limits further egress of wellbore fluid from the wellbore. The methods include preparing a carrier fluid containing compressed expandable foam that may be encapsulated. The carrier fluid is then placed into a lost-circulation zone, whereupon the foam expands to form a barrier that minimizes or blocks further ingress of carrier fluid. Lost-circulation control may be supplemented by introducing additional lost-circulation materials, pumping a cement slurry behind the foam-containing carrier fluid or both.