Based on the Technology-Organization-Environment model we propose a model for explaining the adoption of online appointment schedule platforms by micro-enterprises in order to take the specific characteristics of this organizational type into consideration of technology adoption research. Using case study interviews from seven micro-enterprises we can show that the adoption decision is mainly influenced by the attitude of the entrepreneur, support and updates, scalability, test phase, training and compatibility. In addition, we identify a fourth context of marketing factors relevant for the adoption decision and not considered by the TOE-model so far. Moreover, we discuss whether rather individual- or organizational level adoption models are appropriate to explain the adoption decision of micro-enterprises.