Various forms of chemical resistance testing are used to assess the barrier properties of textile materials when used in applications requiring barrier performance. In most cases, information from this testing is used to support decisions for the development, selection, and use of products that require some level of chemical resistance. One of the foremost applications of textile materials involving the need for chemical resistance is for their use in protective clothing (Fig. 1). As a consequence, many of the chemical resistance evaluation methods have evolved from the chemical protective clothing industry. An important part of this industry has been the establishment of standard test methods that ultimately guide product innovation and claims. While many test techniques have been developed specifically for evaluating protective clothing, they may easily be applied to any use of textile material where chemical resistance determinations are needed. This chapter has been written to provide an understanding of the test methods available for evaluating the chemical resistance of textile materials and is intended to help those with testing needs to correctly choose test methods and interpret test results for chemical barrier performance. Barrier materials are an integral part of protective clothing. Shown here is a proprietary plastic laminate on a nonwoven substrate as part of encapsulating suit for total protection of the wearer. (Courtesy of Kappler, Inc.) https://s3-euw1-ap-pe-df-pch-content-public-u.s3.eu-west-1.amazonaws.com/9780203746684/9fb778d6-9188-497e-bea8-9cc63fb0a90b/content/fig12_1_OB.jpg"/>