To research constitutional history, you must become familiar with the amendment or revision process, and then look for the documents generated by the process.
Generally, state constitutions prescribe four methods for amending or revising a state constitution.
State constitutions are most often amended through the mechanism of legislative proposal. For more information on researching the legislative history of a proposed constitutional amendment, refer to the the following research guide:
Commission-referred ballot measures are ballot measures that are ordered to appear on a state's ballot through the authority of a commission, which itself has been given that authority by a prior act of the state's legislature or in a constitutional amendment.
Example of state constitutional revision commissions include the following:
It is possible to search the Internet to locate digitized commission documents and their finding aids, e.g.:
Search online archives and catalogs of state historical societies:
 Ballotpedia. “Commission-referred ballot measure.”
An initiated constitutional amendment is an amendment to a state's constitution that comes about through the initiative process.
Eighteen states allow voters the right to amend their constitution through the ballot initiative process.
States allowing initiated amendments
Learn the process for initiating amendments – provisions will be found in the state’s constitution or statutes.
Initiative Process in California 
Search for documents
A constitutional convention is a gathering of elected delegates who propose revisions and amendments to a constitution.
Most states have laws that lay out how a constitutional convention can be called in their state. See: Rules about constitutional conventions in state constitutions. There is no provision in the Indiana Constitution for calling a constitutional convention.
The Journals and Proceedings of state constitutional conventions can provide insight into the meaning or intent of constitutional provisions.
The most comprehensive source for such documents is the microfiche collection, State Constitutional Conventions, Commissions, and Amendments, which contains materials published from 1776-1988 for all fifty states. This set comes in five parts (with printed bibliographies). Check IUCAT for holdings in the Law Library and the Wells Library.
Search Library Catalog for print holdings
Digitized, available online