Purpose – The aim of this thesis is to explain the factors that influence consumers’ willingness to contribute to crowdsourcing organizations, by applying the reciprocity theory. Design/methodology/approach – This is a quantitative research which used a cross sectional research design with an explanatory approach. The data was collected with a questionnaire survey that was distributed using face-to-face and online methods. Findings – The findings of this research revealed that social proof is positively influencing willingness to contribute, either direct or indirect, through reciprocity. In addition, trust, commitment and identification were not directly influencing willingness to contribute, however they have an indirect positive impact on willingness to contribute through reciprocity. Research limitations/implications – This study has created a research model by the use of relevant literature in regards to reciprocity and willingness to contribute. Moreover, the limitations of this study are related to the chosen sample, since the generalization of the results is done based on three countries. Practical implications – The study provides some valuable insights for crowdsourcing organizations managers who aim to increase the amount of contributions through their online communities by the use of the reciprocity theory. Detailed explanation goes in the managerial implications section. Originality/value – This research is unique in that it presents a new model that shows reciprocity as a mediating factor for improving online communities’ users attitudes towards contributing to crowdsourcing organizations.