Contemporary evaluations of urban growth management (UGM) strategies often take the shape of quantitative measurements of land values and housing prices. In this paper, we argue that it is of key importance that these evaluations also analyse the policy formulation and implementation phases of growth management strategies. It is in these phases that the institutions and discourses are (trans)formed in which UGM strategies are embedded. This will enable us to better understand the conditions for growth management policies’ success or failure. We illustrate this point empirically with the case of demarcating urban areas in the region of Flanders, Belgium. Using the Policy Arrangement Approach, the institutional dynamics and discursive meanings in this growth instrument’s formulation and implementation phase are unravelled. More specifically, we explain how the Flemish strategic spatial planning vision of restraining sprawl was transformed into one of accommodating growth in the demarcation of the Antwerp Metropolitan Area, epitomised by two different meanings of the phrase “safeguarding the future.” In conclusion, we argue that, in Antwerp, the demarcation never solidified into a stable policy arrangement, rendering it largely ineffective. We end by formulating three recommendations to contribute to future attempts at managing urban growth in Flanders.