 Tillett served on the Joint Steering Committee for the Development of RDA between 1994 and 2012, and served as the committee's chair between 2011 and 2013.Tillett has received numerous awards for her scholarship and work with the Library of Congress, including the ALCTS Margaret Mann Citation, the Library of Congress' Distinguished Service Award and Flemming Award, and the Ross Atkinson Lifetime Achievement Award.In both 2005 and 2007, she was awarded the best paper of the year by the journal "Cataloging & Classification Quarterly".