You can also find much of this data at The Harvard Dataverse Network.
Ethnoregional and Electorally Relevant Ethnoregional Diversity Measures is an MS Excel Workbook with information on two types of ethnoregional diversity measures for 114 countries. The first type is based on the inclusion of all groups. The second includes only electorally relevant ethnoregional groups (EREG). See Minority Rules for more detailed information. The measures are also used in articles listed below and on my CV (link above).
Election Passport has results from legislative elections in over 90 countries around the world from Albania to Zimbabwe. It also details the operation of electoral systems for a variety of countries. Election Passport has now joined forces with the Constituency-Level Election Archive (CLEA) in an effort to make more results available in a uniform format from a single source, though I continue to post election results on Election Passport in advance of its incorporation into CLEA.
Minority Rules contains the data needed to replicate all of the country analyses from Minority Rules: Electoral Systems, Decentralization, and Ethnoregional Parties, as well as many additional variables collected during research for the book. The zip file includes the data in comma-separated variables (.csv) format, a codebook in .pdf and Do-File that permits replication of the country analyses in the book tables in Stata.
Three datasets are posted here that permit replication of the results presented in Table 1 (Italy), Table 2 (Spain), and Table 3 (71 Countries) of “Dispersing Authority or Deepening Divisions? Decentralization and Ethnoregional Party Success,” Journal of Politics 74: 4(October 2012), 1079-93.
Electoral Systems, Ethnic Heterogeneity and Party System Fragmentation contains the data needed to replicate the results from my forthcoming article of the same name in the British Journal of Political Science. You can also find the online appendices here.
Don’t Start the Party contains the data needed to replicate the results from David Lublin and Matthew Wright, “Don’t Start the Party: Assessing the Electoral Effect of Legal Provisions Impeding Ethnoregional Parties,” Election Law Journal 13: 2(2014), 277-87. You can find the online appendices here.
Engineering Inclusion contains the data needed to replicate the results from David Lublin and Matthew Wright, “Engineering inclusion: Assessing the effects of pro-minority representation policies,” Electoral Studies 32(2013), 746-55. You can also find the online appendices here.
Federal Election Project contains the 2000 U.S. election precinct results matched with racial statistics. The National Science Foundation supported collection of this data.
Congressional District Demographic and Political Data, 1972-1994 contains all the data necessary to replicate the results from The Paradox of Representation (Princeton University Press 1997). More generally, this data set contains demographic and political data for congressional districts utilized from 1962 through 1994.
Candidate Quality and U.S. Senate Election Data, 1952-1990 contains all the data needed to replicate the results from “Quality, Not Quantity: Strategic Politicians in U.S. Senate Elections, 1952-1990,” Journal of Politics 56: 1(February 1994), 228-41.