This chapter provides guidance for all sizes and types of organizations and audits of varying scopes and scales, including those completed by large audit teams and those by small teams or single auditors, whether in large or small organizations, and whether for service or manufacturing entities. An auditor is a person or a team of people who have been trained in quality auditing and/or have experience in audit. Audits are mainly classified as: first party; second party; and third party. In the construction sector, quality workmanship provides a competitive advantage in terms of customer satisfaction and loyalty. Quality-conscious organizations provide a safe working environment for their crews and a safe living environment for future users of their construction projects. Auditors must understand that auditing a management system is auditing an organization’s processes and their interactions in relation to one or more management system standards. There are a variety of tools used in auditing, including interviews, review of documents and observation.