The overall procedures for developing composite material static and fatigue design allowables are presented. The allowables are established at the material lamina level accounting for a range of environmental conditions. Design values are derived from an interpolation method, which was confirmed by screening tests. Static test results are presented as a percentage of mean room temperature dry strength and show that the environmental effects are more pronounced for the matrix modes than for the fiber modes of fracture. Kevlar/epoxy is more sensitive to the environmental design conditions than graphite/epoxy. Fatigue test results are presented in a constant-life diagram as a percentage of room temperature wet static tensile strength. The constant-life fatigue diagram shows that the tension-compression and compression-compression range may be the governing aspect for fatigue design. Statistical evaluations are made and indicate normal distribution, and relatively small sample sizes are sufficient to establish reliable design allowables.