Clarity of school rules and teachers' use of praise are strategies suggested to facilitate a positive classroom climate. Studies indicate difficulties for teachers to use such approaches in classrooms with higher levels of disruption. To study (1) if student-rated clarity of school rules, use of praise, and classroom climate differ between students in classes with lower numbers of disruptive students versus classes with higher numbers, (2) if clarity of school rules and teacher's use of praise are longitudinally associated with classroom climate, (3) if the possible longitudinal association differs between groups, classes (n = 109) in school grades 5-7 were divided into two groups, based on head teacher ratings of disruptive students in class. Baseline and 12-month follow-up responses collected within a Swedish trial were used to perform multiple regression analysis, to compare groups and to investigate possible longitudinal associations. Students in classes with less disruption rated all variables more positively. Classroom climate deteriorated over time in both groups, even if the low disruption group perceived their climate as more positive at follow up. Clarity of school rules did not substantially contribute to classroom climate longitudinally, whereas teacher's use of praise to some extent did. The difference in longitudinal associations between groups was marginal, hence our hypothesis on weaker associations in the high disruption group could not be confirmed. Clarity of school rules is not longitudinally associated with classroom climate, but teachers may positively influence the learning environment by giving praise, regardless of level of disruption.