An experimental program to examine the relationship between the material constants of laminates made of unidirectional pües and laminates made of woven fabric composites including plain weave (PW) and eight harness satin (8HS) weave has been conducted. All of the unidirectional and woven composite tension, compression and shear test coupons were fabricated with the same carbon fiber and toughened epoxy resin system. The test specimens were instrumented with back-to-back rosette strain gages and monitored throughout the test. The PW and 8HS woven fabric specimens were tested in both the warp and fill directions. The stress-strain curves of the woven fabric specimens reveal a knee (change in slope) at about 70 ksi, indicating the failure initiation process. The stress field of the weave geometry will be analyzed to understand the failure initiation process.