This document is designed to offer the data reviewer guidance in determining the usability of analytical data generated through the USEPA Contract Laboratory Program (CLP) multi-media Inorganic Statement of Work (SOW), ILM05.X (ILM05.3 and any future editorial revisions of ILM05.3). This guidance is somewhat limited in scope and is intended to be used as an aid in the formal technical review process. It should not be used to establish specific contract compliance (use of this document to evaluate data generated under Inorganic SOWs other than ILM05.X is cautioned). Definitive guidance is provided where performance should be fully under a Laboratory's control (e.g., blanks, calibration verification standards, Interference Check Samples (ICSs), Quality Control (QC) audit samples, and instrument performance checks (tuning)), while general guidance is provided for evaluating subjective data that is affected by site conditions. The guidelines presented in the document will aid the data reviewer in establishing (1) if data meets the specific technical and QC criteria established in the SOW, and (2) the usability and extent of bias of any data not meeting the specific technical and QC criteria established in the SOW. It must be understood by the reviewer that acceptance of data not meeting technical requirements is based upon many factors, including, but not limited to, site-specific technical requirements, the need to facilitate the progress of specific projects, and availability for re-sampling. To make judgments at this level requires the reviewer to have a complete understanding of the intended use of the data. The reviewer is strongly encouraged to establish a dialogue with the user prior to, and after data review, to discuss usability issues and to answer questions regarding the review. It should also be understood that in all Cases, data which do not meet specified criteria are never to be fully acceptable without qualification.