I am trying to create a custom tool in AcrMap 10 that baically allows me to do a select by attribute within the tool. I have a database of river features and want to select features using the river name listed in a column in the attribute table. I can get the tool to the point where, when run, it will prompt me for river name and I can manually type it in and that works, but is there a way to populate a list of options for the parameter so I don't have to know the exact form of the river name to use the tool? Any help would be appreciated.