Historical materialism
Theory of revolution by Karl Marx is a part of his much broader doctrine of "Historical materialism". This theory assumes that "history of mankind is a history of class struggle", what means that whenever you know class structure of any given society, you can understand and predict its behaviour in general. In particular you can predict possibility of a successful revolution.
The class struggle is a necessary part of what Marx called "terms of production". The process of production requires a system of state oppression, allowing a small minority to force the majority to work for its own profit. Without it no achievements of mankind would be possible, from the Egyptian pyramides to the Apollo Project. An essential element of this oppression is the so called "superstructure" - a system of cultural, religious, political and philosophical beliefs, justifying status quo, providing explanations for the misery of the oppressed and welfare of the oppressors: such as "God wants it to be this way" or "it's the American Way of Life".
Means of production are constantly developing, due to invention and competition. There always comes the day, when the superstructure no longer encourages production: on the contrary, it hampers its further development. The modes of production are no longer compatible with modern means of production. But the old ruling class and the old superstructure will never give up without fight. Every superstructure always is based on a fundamental lie, that its principles and values are "eternal" - that, for example, capitalism (feudalism, slavery, etc.) will last forever. And then comes the time for a revolution.
The law of accordance of means of production with modes of production in Marx theory of revolution plays a crucial role, similar to Newton principles in physics. The analysis should begin from a simple question: is the organization of this society encouraging, or hampering development of production? If it is not - the situation is ready for a change.
This theory was drawn mostly from analysis of numerous bourgeois revolutions. It explains perfectly the past, but its prediction of the future is questionable. According to Marx theory, the socialism should appear first in the United States - the mostly developed capitalist country. The scenario should begin with a series of economical crisises, clearly proving, that the capitalism looses control of its own economical resources. This scenario was described vividly by Jack London in his famous novel "The Iron Heel". As we know, actually it never happened (anyway, London predicts socialist revolution in USA for the year of 2169).
In late XIX century numerous modification of marxist theory begun, among others, the leninism proved to be mostly successful (what a pity).