In many countries, policymakers have used urban densification strategies in an effort to create more sustainable cities. However, spatial density as a concept remains unclear and complex. Little information exists about how density is considered by decision makers, including the different kinds of density and the wider political and economic context in which decisions are made: who makes density decisions, when they make those decisions and what they use to make decisions. To that end, the authors created an online survey to investigate the above issues. One hundred and twenty-nine respondents from the fields of architecture, planning, urban design and engineering answered a 26-item survey over a 3-month period. Findings suggest that decision makers consider more than just population and dwelling density and that city design, planning and policy need to address these other kinds of density. Moreover, the professions making many of the density decisions are not, necessarily, the ones that should be making the decisions; nor are they making decisions early enough. Policymakers also need to be more cognisant of the multi-scalar dimensions of density when creating policy. Finally, more needs to be done in universities to ensure that built environment students receive a broader skillset, particularly in terms of engaging with communities.