ABSTRACT. - An international project ('Grass To Gas', 2019-2024) to combine expertise and generate new knowledge for the reduction of the potent methane (CH4) greenhouse gas (GHG) from sheep is underway. Aims are to validate predictors of feed intake, methane emissions and feed efficiency, to investigate the association between feed efficiency and methane emissions measured indoors and outdoors, to explore the opportunity of using genetics and genomics (animal and microbiome) to reduce methane emissions in pasture-based sheep systems and quantify the economic and environmental benefits of more feed-efficient and lower GHG-emitting sheep linked to their microbiome. The potential impact is to deliver applied, sustainable solutions to reduce methane emissions for the international sheep breeding community, by bringing together the latest precision livestock monitoring and molecular technology to identify novel selection targets and potentially candidate genes.