Controlling crystal size distribution (CSD) is important to downstream processing and to product quality. The distribution can be characterized by a mean or dominant size and the spread about the mean or dominant size. The development of tools leading to the control of the distribution in a batch crystallizer is the main topic of the present study. An experimentally based control scheme was implemented for batch cooling crystallization of paracetamol from ethanol solutions. Estimates of the CSD in the batch crystallizer were obtained by applying a model of the octahedral paracetamol crystals to a chord length distribution (CLD) obtained from focused beam reflectance measurement (FBRM) and Lasentec software. The model estimates showed reasonably good agreement with results obtained from sieve analyses performed at the end of the runs.