Balanced scales, that is, scales based on items whose content is either negatively or positively polarized, are often used in the hope of measuring a bipolar construct. Research has shown that usually balanced scales do not yield 1-dimensional measurements. This threatens their construct validity. The authors show how to test bipolarity while accounting for method effects. This is demonstrated on a data set of state and trait anxiety measured with the State-Trait Anxiety Inventory (STAI; C. D. Spielberger, R. L. Gorsuch, R. Lushene, P. R. Vagg, & G. A. Jacobs, 1983) scales. Taking a test-retest perspective, assuming temporally stable method effects, the authors tested the bipolarity of the temporal change through suitable constraints specified in a structural equation model adapted from S. Vautier, R. Steyer, and A. Boomsma (2008). The model fit the data closely, [chi][superscript 2](13, N = 888) = 20.75, p = 0.07. Thus, the state and trait scales seem to measure bipolar constructs plus temporally stable method effects. Parameter estimates suggest reliable change scores for the state anxiety scale (p = 0.90) and specific method effects for the state and trait scales of the STAI. (Contains 4 footnotes, 1 table and 1 figure.)