Indiscipline in Nigerian schools remained a source of great concern to stakeholders as it has caused a lot of mental, emotional, and physical damages in the society. This research investigated the causes of indiscipline among students as viewed by primary school teachers in Nigeria. Furthermore, it also examined the influence of gender, school locale, years of teaching experience, and educational attainment on the respondents' views. This research employed a descriptive survey method involving 200 primary school teachers in Nigeria. They responded to a researcher-designed questionnaire entitled 'Causes of Indiscipline Questionnaire' (CIQ), in which the psychometric properties of the instrument were established. The data were analyzed using both descriptive and inferential statistics. The results revealed that the causes of indiscipline among students as viewed by primary school teachers in Nigeria were societal factor, government factor, parental factor, school factor, and students' factor respectively. In view of the findings it is recommended that the government and school administrators formulate policies in schools to curb indiscipline among students.