Effective distribution coefficients of a binary ideal solid solution growing from dilute surroundings are derived for the steady state using a model in which atoms attach and detach only at kink sites on a (0 0 1) surface of a simple cubic crystal. A system of equations is presented to give the step-edge, terrace, and bulk compositions in terms of attachment and detachment frequencies. The total net flux of atoms from the mother phase to kink sites is also formulated as a function of these compositions and the frequencies. Numerical solutions to the system of equations show that the step-edge, terrace, and bulk compositions are different from one another and that the step-edge, terrace, and bulk distribution coefficients will all approach unity from their respective equilibrium values as the total net flux increases.