We report the synthesis and behavior of thermoplastic elastomers (TPEs) containing both crystalline and glassy hard segments, with the aim of capturing the mechanical properties of conventional all-amorphous triblock TPEs, while forming the solid-state structure by crystallization from a single-phase melt. Living ring-opening metathesis polymerization and subsequent hydrogenation generate pentablock copolymers with the architecture crystalline-glassyrubbery- glassy-crystalline. Analogous crystalline-rubbery-crystalline triblocks show a high initial modulus, yielding, and poor recovery, resulting from plate-like crystalline hard blocks. In the pentablocks, crystallization from a single-phase melt causes a layer rich in the glassy block to form around the crystallites, limiting their lateral growth and generating composite hard domains. The pentablocks show the low initial modulus, strain-hardening behavior, and small permanent set desired for TPEs, while retaining an easily-processed single-phase melt.