This article describes several ways to collaborate between two Office 365 tenants. It is intended for Office 365 Administrators.Suppose that two organizations, Fabrikam and Contoso, each have an Office 365 for business tenant and they want to work together on several projects; some of which run for a limited time and some of which are ongoing. How can Fabrikam and Contoso enable their people and teams to collaborate more effectively across their different Office 365 tenants in a secure manner? Office 365, in conjunction with Azure Active Directory B2B collaboration, provides several options. This article describes several key scenarios that Fabrikam and Contoso can consider.Office 365 inter-tenant collaboration options include using a central location for files and conversations, sharing calendars, using IM, audio/video calls for communication, and securing access to resources and applications. Use the following tables to select solutions and learn more.