The chain folding behavior of oxyethylene/oxybutylene (E/B) diblock copolymers, with one crystallizable E block and one noncrystallizable B block, has been studied by simultaneous SAXS and WAXS, low-frequency Raman spectroscopy, and differential scanning calorimetry. Two models, normal density (ND) and crystal/liquid-crystal (CLC) models were used to explore the results, consideration being given to the difference in the cross-sectional area of the two chains and the need to fill space at approximately normal density. It was found that both models can describe the data for the longer copolymers, but the CLC model is better for the shorter copolymers.