A demand by the GP requiring LPs to fund a portion of their committed capital, also called a drawdown. Typical notice period is 10 business days; the call specifies amount and purpose (investment funding, management fee, fund expenses, organizational costs). A buyout fund typically calls capital at a roughly linear pace over Years 1-4 of the investment period, with some acceleration in Years 2-3. Subscription credit lines can defer LP capital calls by 6-12 months and inflate reported IRR by 100-200 bps; ILPA has called for clearer disclosure.