Open Source Mano is an ETSI-hosted initiative to develop an Open Source NFV Management and Orchestration (MANO) software stack aligned with ETSI NFV. Two of the key components of the ETSI NFV architectural framework are the NFV Orchestrator and VNF Manager, known as NFV MANO. Additional layers, such as service orchestration are also required for operators to enable true NFV services. Open Source software can facilitate the implementation of an ETSI aligned NFV architecture, provide practical and essential feedback to the ETSI ISG NFV and increase the likelihood of interoperability among NFV implementations.