Inserting multiple values into Access97

I have a form for our Intranet that captures and writes information to an Access97 database via a SQL Insert statement. Everything works fine except for the two fields that are populated by drop down lists (which are stored in tables in the same Access database). For every other field multiple values can be entered and they are written to the database correctly, however, from the drop down lists only the first value is written back to the database. How do I get the multiple values in the drop down lists to write to the database correctly? Using an underscore between the values is not an option.