This view holds that Christ will return at the end of the Millennial Kingdom.  Through the spread of the gospel, the world will continue to get better and better until the church "conquers the world" so to speak.  At the culmination of this, Jesus will return to judge the world, sending the wicked to Hell and the righteous to their reward.

During this time, sin will not cease, but it will be minimized because of the influence of the church.  Christ will not physically reign but rather he will spiritually reign through the church because of its vast influence over all facets of life.  (Christ would not need to reign if the church ruled by following His principles.)

The world will witness unprecedented peace as Isaiah 65:20 is realized.  "Never again will there be in it an infant who lives but a few days, or an old man who does not live out his years; he who dies at a hundred will be thought a mere youth; he who fails to reach a hundred will be considered accursed."

The thousand year period does not have to be a literal thousand years.  It may be figurative to simply mean a long period of time.

Like the amillennial view, this view sees the promises to Israel as being fulfilled spiritually with the church.  God is finished with Israel because of their rejection.  See Covenant Theology for more on this. 

It is worth noting that this view enjoyed heightened popularity during the Industrial Revolution in America and England when people saw the world getting better and better and the gospel reaching further and further into the world.  In the 1900's many left this view because two World Wars ruined their optimism for a better world.

See also premillennialism for different views concerning the Millennial Kingdom. 

For further discussion see the article on the Millennial Kingdom.