Ask Yahoo!:

Dear Yahoo!:
Who said, "Actions speak louder than words"?
Aisling
Limerick, Ireland

Dear Aisling:
Talk about a catch-all expression. This proverb can refer to leadership, nuclear deals, taking a stand -- or not, and judo. But, as you might expect, the notion of "What you do means more than what you say" predates modern American culture.

The 16th-century French writer Michel de Montaigne, who is generally credited with inventing the essay, proclaimed, "Saying is one thing and doing is another." And before him, St. Francis of Assisi, who embodied this principle, is widely credited with saying, "Preach the gospel at all times. Use words if necessary."

The present English version of this proverb might date to 1736, but versions of this wisdom are found in many languages and lands, even ancient Greece. Precisely who first said it may be lost to time, but it's a little more certain who first published it on on American shores. In his 1692 book Will and Doom, Gersham Bulkeley wrote, "Actions are more significant than words."

http://ask.yahoo.com/20061227.html