The List class (http://msdn.microsoft.com/en-us/library/6sh2ey19%28v=vs.90%29.aspx) also supports an indeterminate number of items. Given your usage, you may also want to consider using a Dictionary (http://msdn.microsoft.com/en-us/library/xfhwa508%28v=vs.90%29.aspx) as it will provide O(1) access to your data by the field. A dictionary will only work if your field is unique though.