Nutritional status is a measurable and modifiable factor that is often not considered during treatment and its clinical impact undervalued due in part to the heavy demands on clinicians in low and middle income countries to deliver therapy to large numbers of patients. The proposed study will create a biobank of clinical data and biological specimens which will foster future studies on cancer progression and prognosis as well as toxicities during treatment which may impact survivorship and late-effects. Eligible patients must be between 3 years and 18 years of age at time of assent/consent, have newly diagnosed B- or T-cell acute lymphoblastic leukemia or mixed phenotype acute leukemia confirmed by pathology report, and must be receiving treatment at one of the participating centers. Patients receiving hematopoietic cell transplant will be excluded. Institutions were selected to ensure representation of several global health indicators related to nutritional status and wealth classification according to the World Bank. Data related to demographic variables (socioeconomic status, food security), lifestyle habits (diet, physical activity), nutritional anthropometrics (height, weight and arm anthropometry), and nutritional biological indices (stool and blood) will be collected at designated timepoints throughout treatment and one year after the end of treatment.