When Islam first appeared in the seventh century (610 AD), it effected improvements and changes in individual and social life through the following three branches of operation.

1. It brought completely new laws.

2. It prohibited some of the existing laws and customs that were harmful to individuals and the community.

3. It regulated some of the practices and customs making them useful for humanity and with the aim of causing change over time. In these cases, total removal may have introduced greater problems for the society.

The practice of regulated polygamy falls into the third category. Islam did not invent polygamy, but has regulated it. Before Islam, a man could marry as many women as he wanted or could afford to. Islam put a reasonable limit on the number of woman that a man can marry with some tough conditions. It brought the number from the tens to only four. It did not increase the number from one to four.

The verse that allows Muslim men to marry more than one woman is as follows. "Marry women of your choice, two, or three, or four; but if you fear that ye shall not be able to deal justly (with them), then only one." (Qur'an, 4:3). While allowing marriage up to four wives, this verse discourages men from practising it by placing a tough condition of achieving justice between wives and encourages marrying only one. Being just between wives means justice in the provision of food, accommodation, clothing and time spent with each of them. The consequence of this is that a man with four wives must provide four houses and must sleep in a different house every night, only returning to the same house less than twice a week. He must provide food and clothing equally between each of his wives and enjoy their company equally even though one may be twenty and one forty. This is a very tough lifestyle to live for any man. As a result, the great majority (about 99%) of Muslim men have only one wife. This fact is true for all Muslim countries on earth with a slight difference in the marginal rate. This large percentage of monogamy was more or less maintained throughout the history of Islam. According to a survey conducted in the Ottoman archives, the percentage of men married to more than one wife never fell below 92%. That is only 8% of the total male population was married to more than one wife.

According to Islamic Law, if a man were known for his unjust behaviour, he would not be allowed by the state to marry more than one woman at a time. Moreover, a woman can stipulate in her marriage contract that her husband-to-be cannot marry a second woman during the lifetime of their marriage.

Furthermore, if the licence to marry more than one woman is abused or becomes widespread in the society, the state can impose tight regulations to prevent the abuse.

Sometimes polygamy becomes a practical solution to a grave social problem. Throughout history, and still in developing and third-world countries, women depended on men's economic support. Some women may not be able to bear children. In such cases, if the husband wants to have children, he may marry again instead of divorcing his first wife. A 'barren' woman may find it hard to marry again if this weren't permissible. Moreover, after wars, there is usually a shortage of young men. To maintain the stability of the society in such instances, some men should be allowed to marry more than once. More importantly, their second wife should be a widow. For example, after World War I, the famous writer Victor Marqveritte, after the decrease in the male population of France, said the following: "18 million European women have been the victim of the system of living as a widower because of the death of their partners. As a result, they are condemned to misery, economically and morally". Bear in mind that only in the last few decades did women gain economic independence and only in Western countries. Ultimately, regulated polygamy ensures economic security of marginalised women.

In summary, Islam regulated the uncontrolled practice of polygamy and laid some tough conditions for people who chose to enter such a practice. This has greatly reduced its occurrence and polygamy became the exception rather than the rule. Islam has not abolished the practice, as this could lead to social evils of adultery, prostitution and the economic alienation of women. It should be stressed that this is an allowance, not a regular practice. This practice is designed to allow women, generally those that are barren, widowed, or where there are not enough unmarried men, to enjoy a married life where it would not be possible if monogamy was the rule.