Presented at the IIPC Web Archiving Conference, 6-7th June 2019, Zagreb, Croatia. http://netpreserve.org/ga2019/programme/wac/ This paper presents the results of a study to examine, determine and propose the optimal approach to develop impact assessment indicators for the UK Web Archive (UKWA). In the United Kingdom, legal deposit libraries collaboratively operate a nationwide web archiving project, the UKWA, which has collected over 500 TB of data and is growing by approximately 60–70 TB a year. At the same time, UK publicly funded organisations face reduced funding and the challenge of convincing funders to finance their archival function by undergoing evaluations of their services’ values. Under such circumstances, a proper assessment of the values and impacts of web archiving is a point of discussion for cultural heritage organisations. To the best of the authors’ knowledge, there has not yet been a comprehensive assessment or evaluation of the UKWA conducted. Thus, this paper seeks to answer the research question: “What would the indicators of impact assessment for the UKWA be?” As a result, we propose a set of impact assessment indicators for the UKWA (and web archiving in general) with broad strategic perspectives including social, cultural, educational and economic impact. This study examines and proposes the optimal approach to develop impact assessment indicators for the UKWA. The research began by analysing the literature of impact assessment frameworks for digital resources and the types of impact in related fields. Primarily drawing from Simon Tanner’s Balanced Value Impact Model (BVI Model), this research then proposes impact indicators for the UKWA and develops an impact assessment plan consisting of three stages: context setting, indicator development, and indicator evaluation. This paper will present the method and results of the study. Firstly, it identified the UKWA’s foundational context, the mission, the principal values and the key stakeholder groups. The research project prioritised focal areas for the archive that seem most advantageous for stakeholders and aligned with Tanner’s Value Lenses. Secondly, we proposed the UKWA impact assessment indicators; scrutinising existing indicators and various evidence collection methods. In the third stage, the developed indicators’ functionality was checked against set quality criteria and then tested through semi-structured interviews and survey submissions with 8 UKWA staff members. Finally, the paper presents the thirteen potential indicators for the UKWA. Based on the lessons learned, presenters will also make recommendations for organisations which recognise the necessity of undertaking impact assessments of their web archives.