Using continuum elasticity theory, we investigate the stability of coexisting 7 x 7 and '1 x 1' phases on Si(1 1 1) as a function of temperature. We find that of the many possible 'droplet' phases, a configuration in which triangular domains meet corner-to-side is the most stable. At fixed separation, the elastic interaction between two domains is minimized in the corner-to-side arrangement. Away from the transition temperature, the size of the domains decreases while the domain spacing diverges. (C) 2002 Elsevier Science B.V. All rights reserved.