In predicting behavior, behavioral intention is generally the best predictor for behaviors requiring any degree of planning. There are a number of different measures of intention, including measures using percentages to indicate probability, single response measures with response labels to indicate likelihood (e.g. ‘Very likely’), and strength of intention (‘Probably will’). In developing response labels, we also have a choice to develop unipolar and bipolar scales (‘Not at all likely’ to ‘Absolutely Certain I will’ for unipolar; ‘Absolutely certain I will not’ to ‘Absolutely certain I will’ with a neutral point of ‘Uncertain’ for bipolar scales). In a large-scale web-based study with over 12,262 U.S. respondents, we randomly assigned respondents to one of 22 possible likelihood measures to assess likelihood to purchase 8 different consumer products. We compared response differentiation, response extremity, and time of completion. We generally found that unipolar measures of intention had higher correspondence with behavior than bipolar measures, and that measures with response verbal labels had higher levels of validity than did those employing numeric response entry.