Electric motor scooter sharing (ESS) services have been popping up in numerous European cities throughout the last few years. Their marketing targets a young demographic, the sharing service is advertised as both fun and sustainable. Electric motor scooters can indeed be a sustainable mode of transport, for instance, when they contribute to (locally) emission-free transportation depending on the underlying electricity mix (see Weiss et al. 2012). And as we know from former studies, the availability of a city wide sharing system and its usage can decrease the will to buy a private vehicle (see the study from Firnkorn and Müller 2015). Thus, sharing systems got the potential to support multimodal mobility behavior. Besides, when shared, ESS provide relatively space efficient mobility. To evaluate the potential as a sustainable mobility solution, the analysis of mode shift effects created by such a service are a key aspect. Do electric scooter trips mostly replace trips formerly taken by cars with internal combustion engines (ICE)? Or do they replace other trips and possibly create additional traffic? This leads to the main research questions of the paper:•    How does ESS contribute to sustainable urban transportation?•    Which policy regulations or governance solutions are needed to further strengenth the advantages and counterbalance the weaknesses of such a sharing service?The paper does focus on an ESS service run within Munich/Germany. It is based on three types of data: Firstly, automatically collected data concerning customers’ renting behavior allows conclusions on the average customer trip numbers, frequency and lenghts (1). Secondly, a customer survey of the same ESS provides insights on the customers’ trip patterns and mode shift behavior. Besides, it highlights their motivation to use shared electric motor scooters. Via descriptive statistics, the datasets is analyzed using uni- and bivariate approaches. The results are completed by the third type of data consisting of interviews with ESS users on user experiences. (2)The paper features the main results of this study, addressing both ESS strenghts and challenges. On the one hand, it becomes clear to which extent ESS contributes to improving urban mobility, e. g. by replacing trips formerly taken by ICE vehicles and by furthering multimodality (like electrically assisted micromobility options). Furthermore it shows how ESS can improve the image of electric mobility. On the other hand, the paper addresses challenging mode shifts: Which role does the replacement of trips formerly taken by public transport or non-motorized modes of transportation play? And how relevant are trips taken to simply cruise around, thus creating traffic that would have not existed without ESS?Based on the results of the survey and in reflection with city planners, policy recommendations were derivated. Which approaches, instruments or frameworks have to be developed to optimize the sustainable potential of ESS and to minimize risks? The paper concludes with a set of recommendations and push and pull categories in different fields of action such as infrastructural planning, financial instruments, marketing and communication.(1) The data includes almost 490,000 trips.(2) The data was collected as part of the CIVITAS ECCENTRIC research project.The qualitative results refer to the users and their motivations, whereas the analysis of the quantitative data set focuses on substitution effects, the sustainability of ESS on the mobilities system with the aim to make overarching policy recommendations. https://civitas.eu/about The qualitative data was analysed and published in September 2021. https://journals.qucosa.de/jmv/article/view/71