Purpose: In order to get into a profitable business, the various departments must be able to cooperate to not end up in costly conflicts. These conflicts can affect the work morale, the quality of the work done and the schedule can change drastically. Method: A literature study was the basis for gaining a deeper understanding of how internal collaboration works in larger companies. The literature study helped to formulate interview questions, issues and the goals that have been set. A case study was conducted at Peab AB and it was the only company in which the cooperation was investigated. A number of members of the company were chosen as respondents for interviews that became the collected empiricism. In the interviews the respondents were able to describe their opinions on how the internal cooperation works. Findings: The cooperation between departments has a number of conflicts that emerge. These conflicts are often due to time pressure, money, personal chemistry and poor communication. When these conflicts arise the schedules, work morale, cost and quality of the work performed are affected. It may ultimately affect the organisation negatively, which makes it important to get a working cooperation. Implications: If the cooperation fails the company’s results will impair in terms of cost-effective projects, poorer working standards, time losses, and even the quality of the work done. In order to make the internal cooperation work, communication and personal chemistry has to improve. Greater focus on final product has to be implemented and honesty between the departments established. Further research could be to investigate the difference between companies that have construction and infrastructure under the same company and a company that has them under two different subsidiaries. To see the difference in thinking about the end product of a joint venture. Another research might be to investigate how weekly meetings affect the cooperation between different departments, either positively or negatively. Limitations: When the report was first planned and started, the idea was to delimitate the Peab buildings and facilities in Jönköping. The department infrastructure in Jönköping closed its business and the area was forced to expand. The respondents therefore came from Jönköping, Växjö, Linköping and Nässjö. It contributed to a more generalized survey proving that the outcome could be equivalent to the same conditions in the investigation of another company.