This research aims at finding out the effectiveness of jamaah prayer (performing prayer together) habituation in improving the discipline of the students in SMP Muhammadiyah 2 Sendang Agung Lampung Tengah. The research method was quantitative with static design of two groups supported with qualitative method. The respondents were 44 students obliged to perform jamaah prayer in the school (class VIIA and class VIII-A). By contrast, the other 44 students were not obliged to perform jamaah prayer (class VII-B and VIII-B). The data collecting technique used questionnaire distribution, interview, observation, and documentation. The quantitative analysis used the formula of independent sample t- test, while the qualitative analysis used interactive model. After conducting the data analysis, the conclusion is as follows: (1) the discipline of the students obliged to perform jamaah prayer (experiment group) is mostly categorized as very discipline (52.27%); (2) the discipline of the students not obliged to perform jamaah prayer (control group) is mostly also categorized as very discipline (43.18%); and (3) the habituation of jamaah prayer is not effective in increasing the discipline of the students in SMP Muhammadiyah 2 Sendang Agung Lampung Tengah (p = 0.354).