In practice
The investment period is set in the LPA and runs from the first close or initial closing date. It often ends early if a successor fund begins investing or the key-person provisions are triggered, and the LPA may allow an extension with LPAC consent. Some funds permit follow-ons and recycling afterward. It is often called the commitment period.
An example
Round numbers, not a real fundSay a 10-year fund has a 5-year investment period. After year 5 it can still add to existing companies, but it generally cannot buy new ones.
Why it matters
It sets how long the manager can keep putting money to work, and when the fee usually steps down.
A definition, not advice; where usage varies the entry says so. Something wrong? Tell the desk.