Enterprise Resource Planning (ERP) systems have experienced a phenomenal growth in the last 5 years and at present they are pervasive in the US manufacturing sector. This paper describes an attempt to chronicle this phenomenon through a series of case studies and an extensive survey. Manufacturing companies ranging in size from a few million dollars in annual revenues to over a hundred billion dollars are included in this study. The key finding from this study is that companies of different sizes approach ERP implementations differently across a range of issues. Also, the benefits differ by company size. Larger companies report improvements in financial measures whereas smaller companies report better performance in manufacturing and logistics.