This Doctor of Business Administration (DBA) thesis is about identifying the key factors which affect knowledge transfer between individuals in private sector companies in Saudi Arabia and Qatar. A DBA differs from a Doctor of Philosophy (PhD) in its application to live issues rather than the mainly theoretical academic approach in the PhD; is normally business based; and has the potential to make improvement to practice. It is widely recognised that knowledge transfer is fundamental to organisational success and in providing a source of strategic competitive advantage. Middle East countries offer Western businesses growth potential but it is often associated with Localisation of jobs. Successful knowledge transfer could be an important differentiator in achieving Localisation. The aim of this exploratory study was to investigate knowledge transfer between Western Expatriates and Nationals to provide an understanding of the strategic context; to identify the individual key factors involved; to create practitioner guidelines; and to contribute to the academic literature. A qualitative field study, adopting multiple case research design, was used to investigate one company in Saudi Arabia and 2 companies in Qatar. Semi-structured interviews with 31 individuals, based on an existing conceptual framework, were the primary source of data. Direct observation and documentary evidence were secondary sources of data. This study appears to be the first to investigate and compare Expatriate and National knowledge transfer experience in two GCC countries. The main findings were that individual knowledge transfer was being undertaken in the strategic context of Saudisation and Qatarisation. Like other studies, organisational culture and leadership positively and negatively affected knowledge transfer. The positive motivators for Nationals appear to be money, recognition, ambition and self-fulfilment. Their negative motivators seem to be a sense of entitlement and under-confidence. For Expatriates, positive motivators were largely absent whilst a fear of conflict and job insecurity were key negative factors. Expatriate job insecurity led to a Deter-Defer-Delay strategy for knowledge hiding which extends the literature of this emerging concept. Mutual cultural stereotyping also appears to inhibit individual knowledge transfer. The overall practitioner conclusion is that companies should consider how to demonstrate commitment to Localisation through locally adapted policies and leaders should provider commitment and time for knowledge transfer. Nationals need to be selected with values aligned to the company and expectations managed. Expatriates need to be selected and trained to be more culturally aware; have more job security and more organisational support. Future research into Expatriate Deter-Defer-Delay strategies and the testing of the revised conceptual framework, on a longitudinal basis, in other GCC countries, is recommended.