The District of Columbia Official Code (KFD1230 2001 .A22) is a good starting point for legislative history research. The code volumes provide an historical and legislative history note at the end of each section, with references to the date of enactment and Act number, as well as the dates and law numbers of subsequent amendments.
Superseded editions of the D.C. Code are available on the 4th floor in the compact shelving area. Also available on Lexis and Westlaw.
The District's Legislation Information System (LIMS) provides a useful collection of legislative history materials. Resources include bill texts (1989 to present), video recordings of hearings and council meetings (from 2003), and committee reports (1999 to present).
For legislative history information not included in the online collection, contact the D.C. Legislative Services Division, 202-724-8050. The Division maintains files on all bills from 1975 to present, with bill texts, recordings of legislative meetings and committee reports.
Committee reports and bill texts are also available on Westlaw from 2000 to present. Lexis has bills from 2003 forward.