The objective of this study was to compare the fatigue crack growth characteristics of adhesively bonded joints at several temperatures in air and salt water Motivated by current trends in automotive structures, the specimens consisted of urethane adhesive bonding composite adherends with swirled glass fibers in an isocyanurate matrix. A modified cracked lap shear configuration under four-point bending was used to load the specimens, which were reinforced in order to ensure that cracking at or near the interface could be examined under all conditions. Potentially ambiguous diffusion transients were removed by fully saturating the specimens that were to be tested in salt water. Paris Law parameters and threshold values of energy release rate were extracted for each environmental condition that was studied. In air both high and low temperatures increased crack growth rates and reduced threshold values relative to room temperature. Increasing temperature from 10degreesC consistently lowered the bond durability in salt water. The effects of load level, temperature, and environment on the fracture parameters were related to fracture mechanisms via recorded side views and fractographic evidence.