The phase behavior of blends of copolycarbonates containing 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexanone (TMC-PC) and bisphenol-A repeat units with its constituent homopolymers was determined using melt mixing, solution casting, and precipitation casting methods. Miscibility was observed for all combinations except for some involving the TMC-PC homopolymer. Phase behavior was assessed using differential scanning calorimetry and visual assessment of optical clarity. The blending procedure was found to affect the phase behavior in some blends due to interchange reactions and casting methods. Based on the observations of the cast blends, the intramolecular interaction energy of the copolycarbonate was determined to be between 0.029 and 0.036 cal/cc. The phase behavior of these copolycarbonates and a copolyester based on 1,4-cyclohexanedimethanol with terephthalic and isophthalic acids was determined after melt mixing. The copolyester is miscible with all of the copolycarbonates, even in the absence of interchange reactions. (C) 2004 Elsevier Ltd. All rights reserved.