Social applications have been venues for people to converse, emote, and share -- and in those applications, "when" has always been inherent and well captured, but the other contextual signal, "where", has been (usually) conspicuously missing. Location, when taken into account, can provide rich signals to help understand social connectivity whilst helping to discover and surface content. Numerous devices and infrastructure services have the ability to expose location, but comprehending how to best make use of these technologies can be complex. Additionally, after the infrastructure is put in place, the next hurdle to overcome is understanding how to create a useable location-based feature that users can comprehend and love while also feeling safe and secure. This session is targeted to those who want to learn about these technologies, and to those who want to understand how to think about their users' needs, their security, and their privacy. We'll also review web and mobile services that have been designed with location at their core, or location as a feature. And, finally, we'll talk about how Twitter thinks about adding "where" to our "when".