Owing to its enormous capacity, sulfur has emerged as a promising cathode material. Recent studies have identified and begun to mitigate a number of key electrochemical issues in sulfur-based cathodes, including poor conductivity and polysulfide dissolution/shuttling. However, the mechanics of lithiation/de-lithiation of sulfur are much more complicated than in other systems due to solid-to-liquid, liquid-to-liquid, and liquid-to-solid phase transformations, and thus remain poorly understood. To this end, this talk will discuss our recent measurements of the evolution of stresses in composite sulfur-carbon cathodes during electrochemical cycling, performed using an in-situ substrate curvature technique. This mechanical behavior is connected to electrochemical and structural evolution via combined scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction during cycling. Overall, these studies provide fundamental insight into the practical design of mechanically robust sulfur cathodes, thereby paving the way toward realizing new high-capacity systems.