This study aims to shed light on what influences knowledge sharing motivation in startups, which was chosen as the research topic due to its implications for theory development in knowledge sharing and startup fields. Hypotheses related to vision for the company, organizational culture, knowledge sharing motivation and knowledge sharing intention were developed based on a literature review and later tested using Structural Equation Modelling with a novel data set which was gathered from young startups. Vision for the company was found to be linked to all used types of knowledge sharing motivation types while organizational culture was linked to one of the three types. Enjoyment in helping others and reciprocal benefits were found to influence knowledge sharing intention while extrinsic motivators were found to be not influential for knowledge sharing intention.