A developmental chamber is usually smaller than a production chamber and used to perform studies to support Ethylene Oxide validation. This white paper discusses use of a developmental chamber for Process Definition … performed as part of a validation, in adherence with ISO 11135:2014, using the Overkill Approach. Project Management and Quality Assurance personnel within the medical device, pharmaceutical, commercial and food industries will learn what to consider when contemplating either a developmental or production chamber, as well as advantages and disadvantages of using a developmental chamber. As an example, one advantage of using a developmental chamber is that smaller sample sizes in the smaller developmental chamber will often mean lower laboratory testing costs.