Weak increases in classroom cohesion for three seventh-grade classes instructed by a mastery learning technique compared to three conventionally instructed classes are demonstrated using block analysis of variance, triadic census (balance theory), and block modelling (role theory) analytic techniques on repeated-measures sociometric rating data. Each technique is described and clear examples of its use given. Since increased cohesion may have positive effects on student mental health, it is argued that researchers should routinely assess changes in classroom cohesion by these or other methods during classroom interventions. (Authors)