This study focuses on ultrasound-assisted anti-solvent crystallization of lactose, expanding on previous studies and presenting, for the first time, the results of large scale implementation of sonocrystallization for lactose. The results further clarify the interplay between solution chemistry - namely the role of beta-lactose - and crystallization, representing a step forward in the fine tuning of lactose properties for pharmaceutical manufacturing applications. Batches manufactured at laboratory and pilot scales were extensively characterised, including an approach for the quantification of beta-lactose in alpha-lactose based on powder X-ray diffraction (PXRD), which is described here. (C) 2010 Elsevier B.V. All rights reserved.