A "Normalizing Union Query" can move your data into a proper
structure.

First create the target tables - People, Events, Attendance. You know
better than I what fields you now have and what you will need, but at
minimum I'd suggest:

People
 PersonID <Primary Key, autonumber or manually assigned member ID>
 LastName
 FirstName
 <other biographical data as needed>

Events
 EventID <Primary Key, autonumber or manual unique ID>
 EventDate <don't use Date as a fieldname>
 <other info about the event>

Attendance
 PersonID
 EventID
 <any needed info about this person's attendance at this event>

You'll need to manually fill the Events table with the 20 rows for the
twenty events, and note the EventID for each. You can probably run a
simple Append query to append the member information from your
wide-flat table into the People table.

You'll then need to create a UNION query in the SQL window. I don't
know the structure of your table, or whether you have a memberID in
the big table already - I'll assume so, but you can get around the
problem if you don't (post back). Create a new Query, and use View...
SQL. The query will say

SELECT;

Edit this to

SELECT MemberID, (1) AS EventID
FROM wideflattable
WHERE Event1 = True
UNION ALL
SELECT MemberID, (2)
FROM wideflattable
WHERE Event2 = True
UNION ALL
<etc through all 20 events>

The (1) and (2) are the autonumber or manual EventID's for the twenty
events.

Save this query as uniAttendance; then create an Append query based on
it to populate Attendance.

                 John W. Vinson[MVP]