Innovative sustainable transport policies are often tested through experiments or pilots. This chapter focuses on how urban transport experimentation is governed, in today’s context where collaboration and partnerships beyond government are often posited as the key to policy innovation. It critically discusses whether experimentation can be understood as a ‘network governance’ process. First, it analyses the claim that the future role of municipal government is to primarily govern by ‘enabling’ activities led by civil society and private actors. Second, it analyses whether voluntary experiment partnerships based on shared normative sustainability goals are particularly effective for co-creating policy innovations. These two propositions are examined against findings from empirical research on 108 sustainable transport experiments implemented in Bristol and New York City between 1996 and 2016. While non-state involvement and network partnerships were in many cases important for realising transformative impacts from experimentation, they were by no means a precondition. Rather than urban transport experimentation being a network governance process per se, we suggest it reflects ‘hybrid governance’ with multiple co-existing governance modes.