The evaluation of teaching effectiveness in blended learning methodologies is usually carried out using Likert-type questionnaires; however, instruments with Behavioral Anchored Rating Scales (BARS) are sometimes employed for this purpose. This paper examines the validity and reliability of an instrument with BARS designed to assess teaching effectiveness in blended learning environments, within the university setting. The research involves a sample of 1436 students from a medium size university in Spain. Using this sample (n = 1436), the authors carry out a psychometric study that consists of four phases: (1) comprehension validity analysis, (2) construct validity analysis, (3) confirmation of construct validity, and (4) analysis of the instrument reliability. The findings provide satisfactory values for all the parameters analyzed (for instance: Variance explained = 77.61%; RMSEA = 0.042; or Cronbach’s alpha = 0.956), indicating that the BARS instrument examined is perfectly valid and reliable for the appraisal of teaching effectiveness in blended learning methodologies. The authors conclude that this paper fills an important gap in the literature by presenting an instrument that, thanks to the use of behavioral scales, facilitates this task in the university context.