There are increasing demands for the construction industry to improve its processes and learn from past experiences. This thesis begins by examining the need for process thinking in construction. It explores the theories underpinning process improvement, organisational change and learning in organisations, and looks at the relationships between them. The research question of this thesis builds on research carried out within SPICE (Structured Process Improvement in Construction Enterprises), a research project funded by the UK DETR (Department of the Environment and the Regions). SPICE was a response to the Rethinking Construction agenda in the UK, in particular its focus on the construction process. It advocates an incremental approach to process improvement for the construction industry, based on techniques successfully applied in the software engineering industry. The approach of SPICE is taken forward to examine whether process capability assessments can be used to facilitate process improvement and learning on construction projects. A case study methodology is adopted, combining qualitative and quantitative data collected from two UK construction projects. A cross-case analysis is undertaken to answer the research question.