This will be the first multidisciplinary, randomized, longitudinal trial of a tailored, parent- and child-focused physical activity program for children (ages 4- <19 years) with newly diagnosed ALL. It will test the ability of the intervention to prevent or diminish early physical function limitations and improve health-related quality of life (HRQL). The intervention will be tested for its effect on: 1) physical function outcomes (muscle strength, range of motion, endurance, gross motor skills), bone density and bone mineral content (end of therapy only); and 2) HRQL. This multi-site trial will test the intervention in 76 evaluable children with ALL (38 receiving the intervention and 38 receiving a placebo "minimal movement" standard care strategy).

An advanced practice nurse (APN) will meet twice weekly with the patient and family for the first 4 weeks of the intervention to initiate the motivation-based dialogue and therapeutic interaction; this will be followed by once weekly visits during weeks 5-8 of the intervention; and monthly visits during weeks 9-through end of therapy. The physical therapist (PT) will meet at least once weekly with the patient and family during weeks 1-4 to initiate the prescriptive tailored exercise program; subsequent visits to reinforce and modify the program will occur at least once every other week during weeks 5-8, and at least once monthly during weeks 9-135 of the intervention. The PT will visit at least once weekly during weeks 1-4, at least once every other week during weeks 5-8, and at least once monthly during weeks 9-135. During weeks 9-135 of the intervention, the APN will call between the monthly in person-visits, if needed to those randomized to the MAP group to assure fidelity to the intervention and to provide booster support to the intervention where needed.

Inclusion Criteria:

1. An immunophenotypic diagnosis of non-B cell ALL
2. Age 4 years through <19 years at diagnosis
3. 2-8 days on or per front line ALL treatment protocol
4. One parent or legal guardian (≥ 18 years) of the study subject who speaks and understands the English Language
5. Participant speaks and understands the English language
6. Written informed consent and child assent

Exclusion Criteria:

1. Age < 4 years or ≥19 years at diagnosis
2. A diagnosis of cerebral palsy or down syndrome
3. Second malignancy, chromosome breakage syndrome, or severe congenital immunodeficiency
4. Inability or unwillingness of research participant or legal guardian/representative to give written informed consent/assent
5. Females who are pregnant.