Epoxy resin compositions are disclosed which comprise (A) at least one silicone epoxy resin, (B) at least one hydroxyl-containing compound, (C) at least one anhydride curing agent, (D) at least one ancillary curing catalyst, and optionally at least one of thermal stabilizers, UV stabilizers, cure modifiers, coupling agents, or refractive index modifiers. Also disclosed are packaged solid state devices comprising a package, a chip (4), and an encapsulant (11) comprising an epoxy resin composition of the invention. A method of encapsulating a solid state device is also provided.