The past participle proven, originally the past participle of preve, a Middle English variant of prove that survived in Scotland, has gradually worked its way into standard English over the past three and a half centuries. It seems to have first become established in legal use and to have come only slowly into literary use. Tennyson was one of its earliest frequent users, probably for metrical reasons. It was disapproved by 19th century grammarians, one of whom included it in a list of “words that are not words.” Surveys made some 50 or 60 years ago indicated that proved was about four times as frequent as proven. But our evidence from the last 30 or 35 years shows this no longer to be the case. As a past participle proven is now about as frequent as proved in all contexts. As an attributive adjective <proved or proven gas reserves>proven is much more common than proved.