The structure and dipole moments of a series of donor acceptor calixarenes (1-3) containing from four to six aromatic rings have been calculated in their cone conformations using the AM1 method. The nonlinear optical properties of these systems have been evaluated in terms of their first hyperpolarizabilities using a semiempirical sum-over-states approach. All of the calixarenes studied are predicted to have large dipole moments, but their hyperpolarizabilities are critically dependent on the number of excited states included in the evaluation and on the orientation of the donor substituent. An increase in calixarene ring size has only a modest effect on the electronic properties. The limited space at the head of the calix(4)arene ring forces the substituents in both the methoxy (Ic) and methylamino (le) derivatives into unfavorable conformations; which substantially reduces the conjugation between their lone pair electrons and the pi-electron System of the respective aromatic rings to give poor hyperpolarizabilities. When the lone pair electrons of the amino derivative are locked into an orthogonal position with respect to the aromatic ring plane by appropriate bridging alkyl groups, the resulting structure (If) shows considerable potential as a nonlinear optical material for poled polymer films with an extremely large dipole moment of 24.4 D and a calculated hyperpolarizability of 49.9 x 10(-30) cm(5) esu(-1).