This study aims to identify the most valid, reliable and practicable indicators of laboratory mouse welfare using the Delphi consultation technique. The effective assessment of laboratory mouse welfare is a fundamental legal and moral requirement as it is critical part of both maintaining and improving the welfare of the most widely used laboratory animal globally. Although many different welfare indicators are routinely used to assess mouse welfare, the validity, reliability and practicability of many of these measures remains unclear. The Delphi consultation technique is designed to gauge expert opinion through multiple rounds of surveys until a consensus is reached. Participants ranked 59 welfare indicators in terms their validity, reliability and practicability for either a half-day unit audit or a daily welfare assessment and for each scenario identified 10 key indicators. The Delphi consultation reached consensus at 72% for the overall list of indicators and over 60% for each individual indicator. From this consensus the key indicators for each mouse welfare scenario (half day audit and daily welfare assessment) were identified and used to create a welfare scoring system for each scenario.