An emulsion composition for building exterior walls is provided comprising in admixture, [A] a graft copolymerized emulsion obtained by adding to (1) an oil-in-water type emulsion containing at least one organopolysiloxane having an organic group containing a radical reactive group or SH group, (2) a monomer or monomeric mixture containing at least 70 wt % of at least one monomer selected from acrylic and methacrylic monomers and effecting emulsion graft polymerization of component (2) to the organopolysiloxane, and [B] a silicone resin-containing emulsion. The emulsion composition is capable of forming an elastic, flexible coating which is endowed with water resistance, weather resistance, water repellency, adhesion and heat resistance and maintains these properties over a long period of time. It can thus be used as a base in a variety of paints and coating agents.