Growth ring orientation affects many properties of wood. This study was initiated to develop a method for quantifying and classifying growth ring orientation in lumber. The angles of each growth ring are examined using a 45-degree triangle and a ruler. The amount of width containing a flatsawn orientation is determined, providing continuous data. The lumber may also be separated into growth ring orientation classes. If combined with measurements of cross grain, this method may provide a practical technique for characterizing lumber grain patterns. -- AATA