Although polygamy was criminalized by Abraham Lincoln in 1862, it is estimated that 30,000 individuals continue to be involved in polygamous relationships. Some reports put the number of polygamists at 100,000.
Polygamy and the Church of Jesus Christ of Latter Day Saints aka Mormon Church:Although historically, Joseph Smith had dozens of wives and Brigham Young had more than 50 wives, the Church of Jesus Christ of Latter Day Saints will excommunicate any members who condone, encourage, practice, acknowledge, or advocate polygamy. The "great accommodation" which disavowed polygamy in the Mormon Church was passed in 1890.
Polygamy and Sects:Groups such as the Fundamentalist Church of Jesus Christ of Latter Day Saints believe they need to follow the early practice of polygamy as used by Joseph Smith and Brigham Young. They think they need to have at least three wives in order to be accepted into heaven.
Law enforcement leaders are prosecuting more polygamists because the practice often involves forcing young, underage girls into arranged marriages, child abuse, and welfare fraud.
Polygamy in Developing Countries:
Jaan Valsiner: "The usual ('Western') problem of sexual jealousy is largely out of place in the case of non-monogamic marriage forms. Sexuality is a normal part of lives of all participants, male and female. It is regulated for procreational purposes (as the value of it is in having children). It is not expected to be linked with co-wives' feelings towards the husband (who is psychologically distant from the wives anyway - 'love marriages' in the Western sense of recent centuries are not the norm in polygynic cases)."
Source: Jaan Valsiner. Culture and Human Development. 2000. pg. 101.