For a variety of device applications, junction devices in particular, we have demonstrated a heterostructure system of Y1Ba2Cu3O7−y/Y1−xPrxBa2Cu3O7−ywhich maintains epitaxy over the entire Pr composition rangex=0–1. We have grown both trilayer and multiperiod superlattices which show nearly single crystalline helium ion backscattering minimum yields of <6% in the topmost layer. X‐ray diffraction measurements indicatec‐axis orientation by a transverse scan across (005) line with a full width at half maximum of 0.6° and 0.4° on MgO and SrTiO3substrates, respectively. Scanning Auger electron depth profiles and cross‐sectional transmission electron micrographs indicate abrupt Pr/Y interfaces within one unit cell and virtually no disruption of the layered structure at the interface. These results indicate the potential for the growth of excellent heterostructures and superlattices of the high‐temperature superconductors.