Polyspiroacetal polymers and copolymers derived from pentaerythritol, and glutaraldehyde were prepared and examined for physical properties. Elemental and infrared analyses support the polyspiroacetal structure. X-ray analysis indicates a range of 20–40% crystallinity. Dipentaerythritol was observed to influence in varying degrees the crystallinity, the solubility, and the optimum range of film curing conditions. Resins with more than 25% dipentaerythritol always crosslinked during polymerization. In addition, the variables influencing such resin properties as molecular weight and gelation were examined. Films crosslinked with pyromellitic dianhydride exhibited good flexibility and tensile strength. Moreover, their oxidative thermal stability was only slightly less than that of crosslinked poly(ethylene terephthalate).