Thirteen out of 31 extant Norwegian Gothic Painted altar frontals have been examined with regard to materials and technique. A description of their general structure is given, followed by a summary of the analyses carried out on the single paintings. None of the paintings is dated by inscription or document. On stylistic criteria, they have been classified as Early or High Gothic. The paper concludes that a reasonable degree of correlation seems to exist between the stylistic classification and the results of the technical examination. Those paintings classified as Early on stylistic criteria are characterized by two-layer structures with the use of glazes, while those classified as High Gothic are distinguished by opaque one-layer techniques. There are also significant changes in medium, i.e., from oil to tempera as well as use of pigments. Three paintings within the second half of the period have egg tempera as sole medium. The overall change in technique seems to proceed from something complicated towards something more rapid and simple. These changes may have to do with changes in artistic ends, not just with poor economy. See also AATA 18-1434.