INTRODUCTION: Improving menstrual health among schoolgirls is essential to meeting the Sustainable Development Goals (SDGs) of good health and wellbeing (SDG 03), quality education (SDG 04), and gender equality (SDG 05). School participation and wellbeing among girls in low and middle-income countries are impacted by inadequate access to quality menstrual materials and WASH facilities, taboos around menstruation, and poor knowledge. Comprehensive evidence is needed to address these challenges and guide policy and practice. METHODS: An assisted self-completed questionnaire was used to collect socio-demographic information, menstrual-related data, and school climate data from 486 girls in four mixed-gender government secondary schools in Mwanza, Tanzania. The mean (SD) of three Menstrual Practices and Needs Scale (MPNS-36) sub-scores were calculated. Specifically, the extent to which girls perceived needs for carrying and changing menstrual material in school (transport and school environment); washing and drying menstrual material (reuse needs); and privacy and drying menstrual material in school (reuse insecurity) were met. An ANOVA test compared MPNS scores for groups, and logistic regression examined the association between menstrual health and wellbeing outcomes (self-efficacy, menstrual anxiety, school attendance, and participation) and MPNS subscale scores. RESULTS: The mean age of the 486 participants was 15.6 years (SD 1.3); 87% had started menstruating; the mean age at menarche was 14.2 years (SD 1.15). The majority (75%) of girls experienced pain during the last menstrual period, 39% had menstrual-related anxiety, and 16% missed at least one day of school due to menstruation. The mean MPNS subscale score (out of 3) for the reuse needs ranged from 1.0 to 2.1 across schools; 1.6 to 2.1 for reuse insecurity; and 0.9 to 1.8 for transport and school environment needs. The MPNS subscales had sufficient reliability (Cronbach alpha = 0.74 to 0.9). The subscales also had good construct validity with menstrual-related self-efficacy: higher scores for transport and school environment were associated with confidence to seek menstrual support, participate in class, and predict when periods were about to start. CONCLUSIONS: Schoolgirls have unmet needs related to transporting and using menstrual material in school, and these needs differed across schools in northern Tanzania. Menstrual-related pain remains a major reason for poor school attendance and participation. Interventions to address menstrual practice needs in schools are required and should include a strong pain management component.