We present a model of economic growth that is based on Keynesian ideas (the role of autonomous demand in economic growth) as well as Schumpeterian notions (technological change). Our model fits in the Sraffian supermultiplier (SSM) tradition, and we endogenize the growth rate of autonomous demand, and semi-endogenize productivity growth. The basic model has a steady state that is consistent with a stable employment rate. Consumption smoothing (between periods of high and low employment) by workers is the mechanism that keeps the growing economy stable. We also introduce a version of the model where the burden for stabilization falls upon government fiscal policy. This also yields a stable growth path, although the parameter restrictions for stability are more demanding in this case.