This document gives a wide array of target values on nature-based solutions (NBS). In the review, global institutions and their target thresholds for environmental pressures are discussed, as well as individual target values set by European frontrunner cities. It also pays tribute to the proposal by the European Commission for a regulation on nature restoration, for the first time setting concrete targets for increasing urban ecosystem areas. The adopted text by the European Parliament to require Member States to define satisfactory increasing trends at national level for urban green space and canopy cover instead of quantitative targets first proposed in the nature restoration proposal makes this report even more relevant. This deliverable delineates the gaps and needs to define environmental target values as standards throughout European cities. Therefore, the REGREEN project elaborates a typology of target values and illustrates synergies and dependencies between them. Furthermore, the barriers through silo thinking in governance are reflected. They may hinder achievement of NBS targets in cities. Major conclusions are drawn reflecting cross-sectoral insights from scientists, stakeholders and planners. Multiple benefits and trade-offs are discussed to deepen the knowledge of dependencies and synergies between types of targets. Policies demand recommendations and rely on findings like multifunctional benefits from NBS to underpin argumentation. Further interaction and transdisciplinary work must be undertaken to break down barriers and promote implementation of urban NBS. To do so, this document on recommendation of potential target values in cities may aid fostering this interaction.