A capital call is a request made by a venture capital fund to its limited partners (LPs) to contribute a portion of their committed capital to the fund. This is typically done when the fund needs additional funds to make investments or to cover its certain ongoing expenses. A venture capital fund should not commit to a set schedule for capital calls, however, and should call capital only when needed - no significant amount of investors' capital should sit in the venture capital fund's bank account either. 

LPs should be aware that they are expected to contribute their committed capital upon request, and failure to do so may have consequences as outlined in the LPA.