This thesis integrated theories and framework in organisational behaviour and project management disciplines and investigated how organisations can use individualised focused but strategically linked High-Performance Work Practices (HPWPs) and external stakeholder clarity to enhance project success. The research conducted two integrated studies that explored the role of employee engagement, project autonomy and project clarity in the hypothesised direct relationship.

Study 1 (chapter III) drew on the ability, motivation, and opportunity (AMO) framework, and on social exchange theory (SET) to investigate the impact of HPWPs (training, rewards, recognition, continuous feedback and teamwork) on project success, considering efficiency and effectiveness criteria. Further, it explored the role of employee engagement in the relationship. The study relied on a three-wave questionnaire to survey 169 project team members in 33 completed project teams from 12 public and private organisations in New Zealand. Findings from multilevel structural equation modelling (MSEM) with Bayesian estimation analysis indicate that employees’ favourable view of teamwork directly explains project efficiency, and is associated with project effectiveness through employee engagement. Further, project-oriented training and continuous feedback stimulate engagement feelings and behaviours, which in turn influence project effectiveness.

Study 2 (chapter IV) extended study 1 and integrated Human Capital Resource theory, Social Context theory and Shared Mental Model framework to explore the impact of HPWPs (training, recognition, continuous feedback and teamwork) and external stakeholder clarity on project success, considering efficiency and effectiveness criteria. Further, the study explored the role of project autonomy and project clarity in the relationship. Similar to study 1, the second study depends on a three-wave questionnaire to survey 175 project team members in 63 project teams from 20 public and private organisations in New Zealand(teams=23) and nine sub-Saharan African countries.

Findings from the moderation-mediation regression in multilevel structural equation modelling (MSEM) with Bayesian estimation analysis specify those team members that hold a favourable view about the effectiveness of employee recognition tend to complete projects that met the project efficiency and effectiveness criteria. The favourable view of clarity of external stakeholders business needs was directly and indirectly associated with project efficiency via project clarity. Also, the ongoing feedback provided by the project managers explain project efficiency. The positive perception of teamwork effectiveness was associated with project effectiveness criteria.

HPWPs and external stakeholder clarity were antecedent of project clarity. Project clarity mediated the relationship of training and teamwork with project efficiency. On the contrary, the indirect relationship between teamwork and project effectiveness via project clarity was significant but in a negative direction. Project autonomy moderated the mediated relationship of HPWPs and external stakeholder clarity with project efficiency via project clarity. On the other hand, project autonomy moderates the mediated relationship of teamwork and project effectiveness relationship via project clarity in a negative direction. Overall, the study suggests implementing project-specific HPWPs, and initiatives that enhance external stakeholder clarity offer a strategic advantage that helps achieve both tactical and strategic project outcomes.