Organisations invest heavily in knowledge management technologies and initiatives which are entirely dependent on the willingness of employees to share their knowledge. Educational and reward programs need to be informed by an understanding of what motivates people to share their knowledge at work. Prior research based on motivational theories suggests the importance of intrinsic and extrinsic motivators to encourage voluntary pro-social behaviours such as knowledge sharing. However, the literature on motivation in the context of knowledge sharing is still emerging and fragmented. This research-in-progress paper therefore proposes an integrated model that brings together theoretical insights from motivational research to explain the influence of key intrinsic and extrinsic motivators on knowledge sharing. Then the paper reports the results of the assessment of the model based on data collected across 8 organisations in New Zealand. The preliminary discussion of the results contributes to the understanding of motivational factors influencing attitude and intention to share knowledge and their relative importance.