The recent trend in concrete technology towards so-called high-performance, or low water-to-solid binder mass ratio (w/s), concretes has not been without its problems. One of the major problems with these mixtures is their increased tendency to undergo early-age cracking. While this cracking may or may not compromise the (higher) compressive strengths of these concretes, it likely does compromise their long-term durability. The phenomenon of early-age cracking is complex and depends on thermal effects, autogenous strains and stresses, drying, stress relaxation, and structural detailing and execution [1, 2]. In concretes with low w/s, a major contributor to early-age cracking can be the autogenous shrinkage induced by the self-desiccation that occurs during hydration under sealed or partially saturated conditions [3]. As the cementitious materials hydrate under sealed conditions, empty porosity is created within the 'set' microstructure, because the hydration products occupy less volume than the reacting materials. The water menisci created by these empty pores in turn induce compressive stresses in the three-dimensional microstructure. The magnitude of these stresses is influenced by both the surface tension of the pore solution [4] and the meniscus radius of the largest water-filled pore within the microstructure [3]. In this paper, two engineering methods for reducing autogenous stresses and strains by internal water supply are compared: the replacement of sand by saturated low-density fine aggregates (LWA) [5, 6, 7] and the addition of superabsorbent polymer particles (SAP) [8, 9].