Inclusion Criteria:

GROUP A: PATIENTS WITH NEWLY DIAGNOSED ALL:

- Are greater than or equal to 10 years of age and less than or equal to 21 years of
age at diagnosis of ALL

- Have a new diagnosis of untreated ALL classified as "high risk" per NCI criteria (due
to being greater than 10 years of age)

- Are beginning treatment with a Children's Cancer Group/Children's Oncology Group
"high risk" protocol with a 4-drug induction including steroids

- Are not pregnant

GROUP B: EARLY SURVIVORS OF ALL

- Were treated for ALL and remain in first complete remission ("CR1")

- Were equal to or greater than 10 years of age and less than or equal to 21 years of
age at diagnosis of ALL

- Have completed treatment on or as per a Children's Cancer Group/Children's Oncology
Group "high risk" protocol between 12 and 48 months prior to enrollment in this study
(consisting of a plan for a 4-drug induction including steroids in Induction, Delayed
Intensification, and steroid pulses in Maintenance. Steroids are allowed to have
been discontinued due to toxicity).

- Are not pregnant

GROUP C: SIBLINGS OF GROUP A

- Are either a full-sibling or a half-sibling of a patient in Group A

- Are living at the same residence as the sibling/half-sibling from Group A

- Are greater than or equal to 10 years of age and less than or equal to 21 years of
age at the time of study entry, and within 3 years of the age diagnosis of ALL in the
sibling/half-sibling from Group A

- Are on the same Vitamin D supplementation regimen (if any) as the sibling from Group
A at the time of his or her diagnosis

Exclusion Criteria (ALL GROUPS):

- Have a diagnosis of Down syndrome (Trisomy 21) or any genetic disease associated with
abnormal bone development

- Are undergoing treatment with other medicines that affect bones including chronic use
of of steroids, bisphosphonate therapy, or Vitamin D at average dose greater than
400IU/day

- Have an underlying diseases altering body structure (i.e. missing a limb, severe
dysmorphism) or severely affecting mobility (i.e. total or hemiparesis)

- Have a history of chemotherapy or radiation for other cancers

- Cannot complete the radiology exams/radiology exams uninterpretable (i.e. people with
a hip replacement or prosthesis)