Abstract: Improved compositions containing polybutene-1 especially useful for forming articles such as extruded pipe and film comprise a base butene-1 polymer and thermoplastic elastomer comprising a substantially cured mixture of (1) interpolymer of ethylene, polyene and at least one monoolefin having at least 3 carbon atoms, (2) polyethylene and, preferably, (3) at least one polymer of monoolefin having at least 3 carbon atoms, e.g., polypropylene. The thermoplastic elastomer is present in the compositions in an amount sufficient to enhance the characteristics, such as extrusion or molding characteristics, of the compositions. Also disclosed are adhesives and extrusible and moldable materials embodying the compositions of this invention, and processes for forming the compositions into shaped articles which are solvent weldable to other articles such as pipe or film containing the compositions of this invention.