ACTRIS PPP (Aerosols, Clouds, and Trace gases Research InfraStructure Preparatory Phase Project) is a European Project supported by the European Commission Horizon 2020 Coordination and Support Action (INFRADEV-02-2016) from 1 January 2017 to 31 December 2019. ACTRIS Preparatory Phase Project (PPP) will have a significant role in enabling the transition from a projectbased network of research facilities to a centrally coordinated integrated pan-European RI. The main objectives of ACTRIS PPP are to develop the organizational, operational and strategic frameworks of the RI. The work includes legal, governance, financial, technical, strategic, and administrative aspects carried out in 9 work packages. The main outcomes of PPP are signature-ready documents for establishment of a legal entity with well-defined operations and a sound business plan.