Social housing (SH) development is, in general, triggered by policies and regulations, which stimulate interventions, create financing mechanisms, and designate agents conducive to retrofit processes. European directives for energy efficiency and the recent call for a ‘retrofit wave’ have an evident influence. In Brazil, delivery and management of SH are based on the public offer of housing units and their immediate ownership transfer. National or state housing agencies are responsible for basic maintenance for five years, but other post-delivery interventions depend exclusively on the effort and expenses of the occupant. SH budgets leave little or no margin for extra spending and bringing SH to international sustainability standards is yet not mandatory. The issues that arise to implement upgrading in this context are therefore related to the following questions: What are the priority actions in upgrading processes? What type of financing would be required or is available? What is the project execution model and who are the stakeholders involved? This article focuses on the issue of prioritization of actions for upgrading SH. A systematic literature review examined reported sustainability-related housing improvements. A critical review of a Brazilian building label and two international sustainability assessment methods then supported ranking the upgrading actions according to the relevance assigned in their respective contexts. Finally, a panel of construction professionals provided insights regarding the technical feasibility and intrusiveness of their implementation in both single- and multi-family SH projects. Findings show that minor upgrading actions, such as changing hydraulic or electrical fixtures or landscaping, usually do not cost more than implementing them from the outcome and are equally applicable to single- and multi-family SH projects. But, when high-level (deep upgrading) interventions are on the table, costs rapidly increase due to the need to substantially change existing systems or supporting structures, which makes them often financially and/or technically unfeasible.