Abstract: The ultraviolet spectra of a-and P-cyclopropylnaphthalenes (I and 11) resemble those of the corresponding methylnaphthalenes much more closely than those of a-and P- alkenylnaphthalenes. Data are tabulated to support the suggestion that a minimal electron- attracting ability of the naphthalene T system evokes a minimal conjugative response from the cyclopropyl group. To answer the question of the dependence of cyclopropane ...