The effects of convection induced both by diffusion and by the density difference between the solid crystal and the adjacent liquid upon the rate of crystallization are examined in the absence of body forces. Both isothermal and non-isothermal crystallization are considered. When crystallization is taking place in a concentrated solution, significant errors can occur if induced convection is ignored. While diffusion-induced convection can be neglected for sufficiently dilute solutions, ignoring density differences even in this limit can lead to erroneous results.