Green infrastructure (GI) is an important source of ecological habitat and ecosystem services. The potential of the GI in an area to deliver ecosystem services not only depends on the land cover and the habitat types present but also the quality and the localization of the habitats, the so-called ‘service providing unit’ (sensu: Fisher et al. 2009). Environmental and spatial conditions, species composition, use, and management of a particular habitat will determine its performance. However, seldom habitat typologies or land cover classifications are detailed enough to describe the variation in the quality of a particular habitat or land cover type. This not only reduces the feasibility to assess the effectiveness of ecosystem service provision in an area but also yields only limited information about what to do to achieve the required habitat quality to provide the functions and services. For landscape and spatial planning that focuses on defining general development potentials and goals, the lack of a clear GI quality indication may not yet be a constraint. For local landscape design and management plans that seek to realize set objectives regarding ecosystem services and optimize their provision, the lack of detailed knowledge about habitat performance will hinder the proper implementation of the agreed policy. In three closely topic-related cookbooks (nO 2, 3, and 4), we describe the approach used in the IMAGINE project to assess the vulnerability of Green infrastructure to ecosystem degradation, to describe the quality of GI, and to facilitate stakeholders to decide about the management of GI, all concerning the potential of this network to deliver ecosystem services and to sustain biodiversity. The rationale and the methodology may equally inspire and guide other projects where information is needed about the composition and quality of GI networks. When evaluating the quality of a subject, often a distinction is made between intrinsic value and instrumental value. Concerning GI and nature, intrinsic value refers to the perspective that nature has value in its own right (ecocentric values), independent of direct or indirect benefits to man (see e.g. Piccolo, 2017). Instrumental value, on the other hand, refers to the desired end (anthropocentric values), for instance, the delivery of an ecosystem service by a habitat (see, e.g., Kaufman 1980; Maguire and Justus 2008). In IMAGINE, we foremost focus on the instrumental value; the value the GI has to deliver desired ecosystem services. Also, connectedness and habitat suitability of the green-blue network can be interpreted as instrumental as it is a prerequisite to support viable populations. There are many criteria and indicators that can be applied to assess the quality or even ‘health’ of habitats and their networks (see, e.g., Machado 2004; Lu et al. 2015; BISE, Biodiversity Information System for Europe, https://biodiversity.europa.eu/). The selection of appropriate indicators and assessment methodologies very much depends on the level of detail needed for the purpose. More general indicators inform about essential conditions, or about the capacity to resist degradation. Often this approach is applied for region-wide assessments and serves the policy and management decisions taken at a higher level. On the local level indicators will be much more detailed and relate to very specific purposes such as the valuation of habitats concerning the species they sustain, the evolution of habitat quality, or the potential to provide particular ecosystem services.