Miniproteins reduce the complexity of the protein-folding problem allowing systematic studies of contributions to protein folding and stabilization. Here, we describe the rational redesign of a miniprotein, PP, comprising a polyproline-II helix, loop and  helix. The redesign provides a de novo framework to interrogate non-covalent interactions. Optimized PP has significantly improved thermal stability with a midpoint unfolding temperature (TM) of 51C. Its NMR structure indicates a higher density of stabilizing noncovalent interactions than the parent peptide, specifically increased CH-π interactions. In part, we attribute this to improved long-range electrostatic interactions between the two helical elements. We probe further sequence-to-stability relationships in the miniprotein through a series of rational mutations.