​The Natural Capital Coalition, in consultation with companies and organisations, has identified data as a priority area for action. During the pilot phase of the Natural Capital Protocol many of the businesses involved identified challenges around securing access to reliable, complete, and credible data. Others reported that the data required for natural capital assessments is different to that normally collected by companies, and that assessments required a range of sources of data that were not readily accessible. Failure to access robust data in assessments could result in a focus on ‘easier’-to-measure assets, rather than dealing with the real complexities of natural capital. It could also undermine the value of natural capital assessments as a decision-making tool. Providing companies with guidance on key natural capital datasets, their limitations, and how to overcome them, will enable more rigorous natural capital assessments and better management of risks and opportunities. To address this, UN Environment World Conservation Monitoring Centre (UNEP-WCMC) is working with businesses on behalf of the Natural Capital Coalition to deliver the ‘Data Information Flow’ project. This review forms part of phase 1 of the Data Information Flow project, delivered by UNEP-WCMC on behalf of the Natural Capital Coalition. This report is based on: (1) a survey of the Natural Capital Coalition’s network on data needs, sources, challenges, and solutions; (2) structured interviews with 10 organizations representing different aspects of the ‘natural capital data ecosystem’ (defined below); and, (3) a review of existing data standards and guidance. It also draws from consultation sessions and Protocol Application reviews conducted from 2015–2017. This review seeks to assist companies in dealing with the data challenges they face when carrying out natural capital assessments.