Background Although recognised as essential, the role of local governments in promoting health remains under investigated. Yet their mandate directly impacts living conditions and promotes SDGs. In France, 'local health contracts' (LHCs) mobilise local decision-makers in 4 areas: health promotion, prevention, health care and social care. The CLoterreS study assesses the extent to which LHCs foster health-promoting actions through cross-sectoral collaboration. Methods We conducted 49 semi-structured interviews with staff from all Regional health agencies (RHAs) and local stakeholders. We analysed the action plans of a stratified random sample of 53 LHCs from the 165 signed between 2015 and March 2018. We used a validated multidimensional coding tool based on WHO's Essential Public Health Operations and other consensus documents. Results LHC's contribution to health promotion through cross-sectoral collaboration depends on a mix of factors. Among barriers, the improvement of access to health care is often a primary driver for local elected officials. However, political will and past experience in establishing 'win-win' relationships with other sectors is an advantage, as well as the fact that RHAs generally make LHCs an instrument to coordinate health promotion efforts instead of ad hoc funding of isolated actions. Overall, 73% of LHCs' actions address living conditions, health promotion or primary prevention. LHCs frequently target behavioural determinants such as physical activity or diet (44 out of 53) with an emphasis on individual or interpersonal targets. A few innovative actions situated at the intersection of urban planning, transportation, recreational or food environments illustrate the potential for further cross-sectoral action on living conditions. Conclusions LHCs are vehicles for health promotion. Reinforcing cross-sectoral action implies leadership, resource mobilisation, training and coordination of sectors whose health is not a core priority. Key messages In France, Local health contracts (LHCs) are significantly used for health promotion. Cross-sectoral collaboration in this area implies further capacity building beyond the health care sector at the regional and local levels.