In order to inform the development of future interlaboratory studies for permeation test standards, a review on sources of variability in permeation testing, the findings of past interlaboratory studies performed, and methods of categorizing chemical protective clothing (CPC) permeation performance is presented. Specific recommendations are made for the improvement of a future interlaboratory study for ASTM F739, Standard Test Method for Resistance of Protective Clothing Materials to Permeation by Liquids or Gases Under Conditions of Continuous Contact. More data fields should be collected from testing laboratories in order to relate results to differences in analytical techniques and collection methods. A more complete range of test materials should be used in order to represent a range of CPC performance criteria.