With rapid worldwide urbanization it is urgent that we understand processes leading to the protection of urban green areas and ecosystems. Although natural reserves are often seen as preserving 'higher valued' rather than 'lower valued' nature, it is more adequate to describe them as outcomes of selective social articulation processes. This is illustrated in the Stockholm National Urban Park. Despite strong exploitation pressure, a diverse urban movement of civil society organizations has managed to provide narratives able to explain and legitimize the need for protection-a 'protective story'. On the basis of qualitative data and building on theories of value articulation, social movements, and actor-networks, we show how activists, by interlacing artefacts and discourses from cultural history and conservation biology, managed to simultaneously link spatially separated green areas previously seen as disconnected, while also articulating the interrelatedness between the cultural and the natural history of the area. This connective practice constructed holistic values articulating a unified park, which heavily influenced the official framing of the park's values and which now help to explain the success of the movement. In contrast to historically top-down-led designation of natural reserves, we argue that the involvement of civil society in protecting nature (and culture) is on the rise. This nonetheless begs the question of who can participate in these value-creating processes, and we also strive to uncover constraining and facilitating factors for popular participation. Four such factors are suggested: (i) the number and type of artefacts linked to an area; (ii) the capabilities and numbers of activists involved; (iii) the access to social arenas; and (iv) the social network position of actors.