The structural origin of the enhancement of the electro-optic (EO) activity of a dendrimeric material, relative to the traditional guest-host polymer, is established within an analytic model. Chemical bonding between the chromophore fragments in the dendrimer suppresses the antiferroelectric correlation of the chromophore dipoles and assists in the macroscopic ordering of the dipoles by an applied field. The developed analytic model quantitatively agrees with the experimental data both for the increased EO coefficient of the cross-linkable dendrimer, and the decreased EO coefficient of the non-cross-linkable dendrimer. The model facilitates optimization of the structural and molecular properties of dendrimers and chromophore fragments in order to achieve materials with better EO response. (C) 2003 Published by Elsevier Science B.V.