Cem Tecimer (a doctoral student at Harvard Law School) and I have been busy on a project that centers around a simple question: what relevance do past constitutions have for interpreting and applying an existing constitution? One answer might be: no relevance because a new constitution is, well, new. But that isn't the answer most courts give. Instead, courts (and other constitutional interpreters) routinely make use of predecessor constitutions to interpret the in-force constitution. Cem and I call this practice interconstitutionalism. Cem and I have gathered hundreds of examples of the practice from the state courts (half of the states have had more than one constitution) and from courts in other nations that have had multiple constitutions. We have also looked at uses of the Articles of Confederation in interpreting the U.S. Constitution (recognizing there is some debate about whether the Articles should be deemed a constitution) and uses of the U.S. Constitution in interpreting the confederate constitution. Interconstitutionalism has lots of dimensions (some very surprising) and some interesting implications for thinking about constitutional interpretation, constitutional change, and popular sovereignty. For example, many state courts take the position that in discerning the original public meaning of a constitutional provision, the relevant point in time is not when the existing constitution was ratified but when the provision first occurred in a constitution of the same state. The more we dig the more topics emerge and so we anticipate multiple papers from the project. The draft of our first paper is now posted here. We will be glad to hear about additional examples or other lines of inquiry that occur to readers. My e-mail is mazzonej[@]illinois.edu.