In 1991 the Bureau Commune de Reference (BCR) of the Commission of the European Communities funded an inter-laboratory comparison of angular dependent optical properties of architectural glazings to establish the state-of-the-art of such measurements in European laboratories. The inter-comparison was performed amongst 12 laboratories in 8 countries and the European glass industry was represented by 4 major companies. Measurements were made of the spectral transmittance, T(lambda) , and spectral reflectance, R(lambda) , on three samples of architectural glazing at 10 degree(s) and 60 degree(s) angle of incidence for both s- and p- polarization of the incident beam at wavelengths in the visible and near infrared regions of the solar spectral range. The technical objectives of the intercomparison were to assess the applicability of the different measurement techniques employed by the participants, to establish confidence levels for angular dependent transmittance and reflectance measurements, to identify sources of measurement error and to evaluate potential calibration and reference materials.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.