A package endures a broad range of physical conditions. Container qualification testing labs can simulate and evaluate a package’s response to: shock, vibration, and shock vibration testing, compression testing, climatic conditions such as: high temperature/low temperature testing, humidity, altitude, and much more. Therapeutic products come into direct contact with packaging systems and their plastic materials of construction as the product is manufactured, stored, and administered. Such contact may result in an interaction between the therapeutic products and the packaging systems and its materials or components of construction. These interactions must be such that the suitability for use (including its safety and efficacy) of the therapeutic product and the packaging systems is not adversely affected by the interaction. Although suitability for use includes several quality aspects of the packaged drug product and its performance, the suitability for use aspect addressed in this chapter is patient safety. Obtaining such a necessary and desirable outcome is facilitated by the use of well-characterized plastic materials of construction in components, containers, and packaging systems and by the appropriate testing of packaging systems. There are a number of USP, EP, JP and FDA compendia procedures designed to ensure that the container composition and functionality is appropriate for pharmaceutical products in various phases. Pharma Product Testing service providers utilizes these compendia methods, as well as client-supplied procedures for container analysis, including: Permeation Testing; Extractables Testing; Functionality Testing; Identification Testing. Establishing the suitability of plastic packaging systems for therapeutic products involves multiple tests and testing procedures, such as: Material screening: Characterization of a packaging system's materials of construction to evaluate ingredients as probable extractables and potential leachables. Such a characterization facilitates the identification of materials that are suitable for use in packaging systems; Controlled extraction (simulation) study: Worst-case controlled extraction (simulation) study to determine the extent to which extractables may become probable leachables; Product assessment: Actual-case measurement of confirmed leachables in the therapeutic product in the pharmaceutical packaging/delivery system intended for the commercial market.