Future scenarios are often used to address long-term challenges characterised by uncertainty and complexity, as they can help explore different alternative future pathways. Scenarios can therefore be a useful tool to support policy and guide action towards sustainability. But what sustainability aspects are put forward in scenarios and how are they assessed? This paper aims to explore how to assess future scenarios, categorised according to Börjeson et al. (Futures 38:723-739, 2006) i.e. predictive, explorative and normative scenarios. By conducting a literature review and a document analysis, we map tools and methods that are currently used to assess environmental and social sustainability aspects in scenarios. We also draw on experiences from methods for impact assessments of Swedish municipal comprehensive plans, which can be considered as future scenarios. We identify whether some sustainability aspects are less recurrent than others in the reviewed assessments or even left out. We find that there is no single tool that can be used to assess scenarios. Some quantitative tools based on databases may be more suitable for assessing scenarios within a shorter time horizon, whereas qualitative assessment methods might better fit the purpose of long-term transformative scenarios. We also find that assessment frameworks may be useful to guide the assessment, as to what its intended purpose is and which sustainability aspects to include. Finally we discuss whether further assessment tools are needed in order to include a wider array of potential environmental or social consequences of the content of scenarios.