categories of internal and external constraints. Compared to the external factors, the internal constraints were found to contribute far more to the onsite labour productivity issues in the New Zealand construction industry. In the order of decreasing influence, the internal factors comprise project management, project finance, workforce, project characteristics and technology/ process. The key subcomponents under each of the five broad categories of the internal constraints are rework; level of skills and experience of the workforce; adequacy of method of construction; buildability issues; and issues around coordination, supervision and performance monitoring and control; respectively. Under the three external constraint broad categories, the key subcomponents are compliance with the Resource Management Act 1991; ground conditions; and the boom-bust cycles, market conditions and level of competition in the industry; respectively. In addition to understanding the nature of the identified constraints, some mitigation measures have been discussed for addressing the key subcomponent under each broad constraint category. In conclusion it is believed that by focusing on the relative levels of impact of the identified constraints, the project team could be guided well in their efforts to addressing the constraints in a cost-effective manner. Recommendations for Future Studies This study focused on constraints to construction on-site productivity; however, there are several aspects to construction productivity. Future studies should explore other influencing factors affecting construction productivity at all stages of the procurement process. As demonstrated in the demographic analysis of the respondents, the responses were largely from contractors and project management consultants. The results did not include many inputs from subcontractors who provided only 8 percent of the responses. It may be necessary to aim for representative feedback from subcontractors in future studies, as they are the key players on construction sites. Also there was absence of feedback from clients and designers. Further studies should also seek to capture opinions of these stakeholders as they significantly influence on-site procurement processes and performance outcomes.