 However, despite this spirit being embraced by many scientists, data sharing remains the exception rather than the norm in contemporary systems neuroscience. The Allen Brain Observatory, ABO, is an example of an initiative that seeks to promote open data sharing and reuse. ABO has shared data and metadata associated with surveys of neuronal activity in the visual system of laboratory mice, which has led to over 100 publications and preprints. This paper summarizes some of the lessons learned from ABO, such as remaining barriers to data sharing and how they can be addressed. This article was authored by Saskia E. J. De Vries, Joshua H. Siegel, and Kristof Koch.