Knowledge management (KM) has been studied extensively in recent years. Some consider knowledge to be the most strategically important resource for any company, but the fragmented, project-based and task-oriented nature of construction work makes it more difficult to implement KM in this sector. This paper presents a survey of perceptions of KM implementation in the Spanish construction sector and compares the results obtained from design and construction firms. Data were collected from the leading civil engineering companies in Spain. The survey found that the Spanish construction industry is aware of the benefits of KM but that systematic KM is not generally implemented. The findings clearly demonstrate that changes in organizational culture are critical to successful KM. The survey also revealed some distinctions between the KM perception of design firms and that of construction firms.