A study conducted in Columbus, Ohio, assessed the importance of voter uncertainty in motivating media use and use of specific campaign information. Data were collected from a telephone survey of 540 persons registered to vote in Columbus or surrounding Franklin County. Decisional difficulty, likelihood of vote change, and knowledge about the strengths and weaknesses of the candidate were measured as types of certainty. For the candidate uncertainty measures, results indicated that those voters who rented rather than owned homes, those less than 40 years in age, and females tended to be significantly more uncertain. Independents were also more likely to be uncertain than Democrats and Republicans. Younger voters and females reported being more uncertain about the gubernatorial race. Independents and Republicans were significantly more likely to think they would change their vote choice for governor than were Democrats. For the uncertainty measure based on knowledge of candidate strengths and weaknesses, no significant differences in demographic or partisan groups emerged. Of importance was the finding that knowledge measures were not always satisfactory measures of uncertainty. Many voters who were low in knowledge did not report that their voting decision had been difficult or that they were likely to change their vote. (HOD)