This updated edition of the Laboratory Manual for Wineries is intended for those wishing to conduct general labora­tory analyses of grape musts and wines. Determinations of sugar, sulfur dioxide, titratable and volatile acidities, pH, and alcohol content are integral measurements performed by commercial and home winemak­ers. While these determinations allow chemical adjustments to musts and wines, they are also critical for compliance with state and federal laws regarding composition (e.g., alcohol, volatile acidity, and sulfur dioxide). One area that the authors address throughout this manual is the question of quality assurance regarding laboratory results. Wine statistics are notoriously difficult to compare between wineries due to variability in methods and practices between laboratories. In fact, win­eries occasionally encounter difficulty in obtaining reproducible results even within the same laboratory. Herein, the authors have suggested some controls that will help wineries address these issues.