Numerous studies have expounded on the benefits of social support for health, yet not all of us have access to extensive social support networks or supportive group therapy. Even fewer of us have constant access to such support. Mobile technology can help to bridge this gap by connecting individuals with one another regardless of time or place, but mobile phones are an imperfect medium for engaging in socially supportive activities, partly because of form factor issues (small screen, no keyboard) and partly because of the inability of computers to understand human emotion. Design and evaluation considerations for mobile emotion sharing systems are presented and the building and evaluation of such a system, Aurora, is described. Aurora and the study presented here represent first steps toward that end, examining (1) how well users are able to share emotions using abstract representations of emotion such as colors and photos, (2) whether users prefer sharing emotions using colors or photos, and (3) whether such a system is viable and enjoyable in mobile contexts. Aurora users were able to share emotions using either colors or photos? particularly when supplementing them with textual notes, they preferred photos to colors, and they enjoyed sharing emotions on their mobile phones, even with strangers. These findings have implications for how one thinks about designing emotion-sharing technologies in the future and for uses of such technologies in the context of social support and health.