Exhibit 1.1 VAN KAMPEN UNIT TRUSTS, SERIES 790 TRUST AGREEMENT Dated: September 2, 2008 This Trust Agreement among Van Kampen Funds Inc., as Depositor, The Bank of New York Mellon , as Trustee, Van Kampen Asset Management and Cohen & Steers Capital...Trust Agreement • September 2nd, 2008 • Van Kampen Unit Trusts Series 790
