Abstract: In recent years, the integrodifferential equation has been used to model biological aggregation and dispersion. During this talk, we discuss recent work on existence, uniqueness, and finite-time blow-up of solutions to this equation for nonnegative initial data belonging to . For kernels which are rotationally invariant, nonnegative, and decay at infinity, finite-time blow-up is proven when has a Lipschitz point at the origin.