Scottish journalist, editor of the 6th edition (1820–23) of the Encyclopædia Britannica and cofounder and editor of The Scotsman (1817), Scotland's first independent Liberal paper. He also performed editorial services for the 4th, 5th, and 7th editions of the Britannica.

With the help of friends, Maclaren launched The Scotsman in 1817. As its political editor and, later, controlling editor, he shaped the paper's policies, supporting reform at home and liberalism abroad. His services to science were recognized by election to the Royal Society of Edinburgh (1839) and to the geological societies of London and of France (1846). In 1864 he became president of the Geological Society of Edinburgh.