The semicrystalline morphology of a series of poly(ether ether ketone) [PEEK]/poly(ether imide) [PEI] blends has been investigated as a function of blend composition and crystallization condition by dielectric relaxation spectroscopy. Dielectric scans of the crystallized blends revealed two glass-rubber relaxations for all specimens corresponding to the coexistence of a mixed amorphous interlamellar phase, and a pure PEI phase residing in interfibrillar/interspherulitic regions; no (pure PEEK) crystal-amorphous interphase was observed. Variations in the composition of the mixed interlamellar phase with crystallization temperature were consistent with kinetic control of the evolving morphology : lower crystallization temperatures led to an increase in the amount of PEI trapped between crystal lamellae. Comparison of the relaxation characteristics of the interfibrillar/interspherulitic phase with those of pure PEI indicated a much broader spectrum of local relaxation environments for PEI in the blends, consistent with PEI segregation across a wide range of size scales.