Quasielastic and static light scattering techniques were used to investigate the effects of the addition of 1-pentanol on the size and shape of sodium dodecyl sulfate (SDS) micelles in 0.3, 0,4, and 0.5 M NaCl-H2O solutions at 25 degrees C. For each salt concentration the concentration of 1-pentanol was varied from 0.00 to 0.1 M, in steps of 0.01 M. The data show characteristics of a continuous sphere to rod transition. This transition was observed by determining the mean hydrodynamic radius, [R(h)], using quasielastic light scattering and by using static light scattering to calculate the mean radius of gyration, [R(g)], for micelles with [R(h)] greater than 12 nm, the Limit of our instrument. A combination of the two measures of micellar size shows that the micelles can be modeled as flexible wormlike objects.