When considering a bill, Congress may hold hearings to find out more about the subject matter of the legislation or to determine how different interest groups feel about the issues involved. Committee hearings can be good sources of information on a particular topic, but they are less useful in determining Congressional intent because the views presented in a hearing are the views of the witnesses rather than members of Congress.
Hearings consist of transcripts of oral testimony and may also include prepared statements or written reports or studies presented to the committee by the witness. Official hearings publications are printed by the Government Printing Office and contain all witness testimony, the question-and-answer portion of the hearing, and any other material requested of the witness by the committee. It takes several months, or even years, for a hearing to be published, and not all hearings are published. Until official publication, it may be that all that is available are individual transcripts of testimony. Two commercial services, Federal News Service and CQ Transcripts, selectively transcribe committee hearings and provide them to LexisNexis and Westlaw (see below).
The Regenstein Library has a complete set of all published Congressional committee hearings. The D'Angelo Law Library has a complete set of all House and Senate Judiciary Committees hearings since 1935 in print. All hearings are published with a title indicating the name of the committee and date of the hearing. Once you have identified the title of a hearing using ProQuest Congressional, consult the Library catalog to get the call number and location.
ProQuest Congressional is the best place to start to identify and find Congressional hearings. It provides index information and abstracts, as well as direct access to the full text in PDF when available. The Congressional Hearings Digital Collection provides full text PDF access to both published and unpublished hearings from 1824 to the present. Index information includes information such as the name of the hearing, its SuDoc number (if applicable), a brief description of the purpose of the hearing, and a list of witnesses. Abstract level coverage provides some more details about the substance of the testimony presented at the hearing.
Keep in mind that not all hearing transcripts are published, and that the electronic text versions of hearings available through ProQuest Congressional, LexisNexis, and Westlaw may not include everything (especially appendices) from the official printed version. In some instances you may be able to find hearing documents from recent hearings on the website of the Senate or House committee or subcommittee that held the hearing.