Cultural differences and misunderstandings contribute to project complexity. As many complex projects involve multiple organisations and/or are conducted internationally, this chapter summarises what project leaders should consider when programmes and projects cross cultural boundaries. Time is the issue that most emphasises cultural differences and produces frustration for project teams when working with other organisational cultures. Organisational cultures can range from results-oriented cultures to cultures that favour work-life balance. The project culture contributes to the development of the team spirit within the project and it provides orientation to the team members. A check on cultural fit at the beginning of the programme or project should indicate where potential difficulties might occur; which organisations should work together well and which organisations will have cultural misalignments. Even within one organisation different departments may have different cultural habits. Generational culture adds another dimension to interpersonal harmony and team productivity.