A theory of the mass distribution of interplanetary particles has been developed and it has been shown that, provided the solid debris resulting from the erosion due to mutual collisions is not important, then the asymptotic mass distribution is a power law. The predictions of this theory are compared with observations, and very good agreement is found in the case of meteor streams and asteroids > 2km in diameter. For sporadic meteoroids it was found that a second process was needed to explain the observed mass distribution, and the condensation of some components of the interplanetary gas is shown to be consistent with observation.