Lawrence Tesler, a pioneering computer scientist who helped make it easier for users to interact with computers, whether cutting and pasting text or selecting text by dragging a cursor through it, died on Sunday at his home in Portola Valley, Calif. He was 74.

The cause was not known, his wife, Colleen Barton, said, but in recent years he had suffered the effects of an earlier bicycle accident.

Mr. Tesler worked at a number of Silicon Valley’s most important companies, including Apple under Steve Jobs. But it was as a young researcher for Xerox at its Palo Alto Research Center in the 1970s that he did his most significant work: helping to develop today’s style of computer interaction based on a graphical desktop metaphor and a mouse.

Early in his Xerox career (he began there in 1973), Mr. Tesler and another researcher, Tim Mott, developed a program known as Gypsy, which did away with the restrictive modes that had made text editing complicated. For example, until Gypsy, most text-editing software had one mode for entering text and another for editing it.