When the first object oriented programming language was introduced, it gathered lots of interest and began to grow rapidly. This led to the emergence of many object oriented design methods. With all these design methods came numerous modeling languages and by the early 1990s, many object-oriented modeling techniques were being developed to model software. There were different approaches to using different modeling techniques. Some techniques were designed just for application modeling, and others were targeted at specific areas such as database design. Each one had its strengths and weaknesses. Darwinian forces in the marketplace led to three dominate methods, each having its own modeling language. With three of these methodologies leading, Rational software hired James Rumbaugh after he developed object modeling technique while working for General Electric previously. With Rumbaugh on board, the company was known for two of the most popular object-oriented modeling approaches. The first one being Rumbaugh’s object modeling technique and the other being Grady Booch's object oriented design. Next they were assisted by Ivar Jacobson who developed object-oriented software engineering and Jaconson joined Rational shortly.

The three of them together at Rational developed the unified method version 0.9 in 1996. The aim is not to create a new series of symbols but to but to adapt, expand, and simplify the existing and widely used object oriented methods. Other well-known companies started to join them to further the development of unified method. In 1997, they developed version 1.0 which was then renamed to unified modeling language (UML) and the latest version UML 2.5 was released in October 2012.