The rapid growth of using Web 2.0 tools such as blogs has increased online courses in education. Questionnaires are the most commonly used instruments to assess students' attitudes toward the online courses. This study provides a set of specific guidelines that the researchers used to develop a questionnaire to measure students' attitudes toward the course blog. It focuses on test construction and instrument validation as two primary stages in developing the questionnaire and details a series of steps nested within two stages. Participants were 30 undergraduate students enrolled in a course blog. To analyze the data, qualitative findings of interview were complemented by statistical results from quantitative data. To improve content adequacy and internal validity of the instrument items, 25 students who took part in piloting the instrument were interviewed. We carried out Statistical analysis to evaluate inter-item correlations, and reliability alpha coefficient of the instrument items. The guidelines applied in this study can be used in other studies to develop a valid instrument to measure other constructs, particularly when a researcher does not have access to a large sample. (Contains 1 figure and 2 tables.)