In addition to shifting the melting point, the sidechain energetic parameter ε S significantly increases the height and sharpness of the heat capacity peak, and therefore the cooperativity of the folding transition. While the sigmoid width (d) is roughly equal (within the bootstrapping uncertainty of 1 standard deviation) for all σ S considered at high ε S , at low ε S it is clear that the intermediate σ S parameter (1.556σ B ) results in the strongest cooperativity. In contrast, the smallest σ B leads to the weakest cooperativity at low ε S . This is expected since the range of the sidechain interactions is small for low σ B . The heat capacity FWHM results mirror these trends in cooperativity, with the moderate σ S exhibiting the sharpest heat capacity peak for all ε S .