DateTime fields store date and Time so if you are using Between '6/1/08' and '6/30/08' then you are actually saying give me all the data From 6/1/08 00:00:00 to 6/30/08 00:00:00 so you will not get results for 6/30/08 00:00:01 and later. This is why most people recommend using date >= '6/1/08' and date < '7/1/08' instead of between for date ranges. Now in SQL Server 2008 with the new Date datatype your between would do what you think it would.