Inclusion Criteria:
* A diagnosis of osteomyelitis (first episode) defined by:
* Pain or point tenderness upon palpation or probing to bone
* Plain radiograph or Magnetic resonance imaging (MRI) consistent with osteomyelitis (indistinctly marginated edema-like pattern of bone marrow hypointensity on unenhanced T1-weighted sequences, hyperintensity on fat-saturated T2-weighted and Short tau inversion recovery (STIR) sequences and/or abnormal enhancement on gadolinium-enhanced fat-saturated T2-weighted sequences, with or without visible periostitis or cortical bone destruction) OR Gram-positive cocci documented on a baseline Gram-stain from a bone specimen
* Elevated C-reactive protein (CRP) (low sensitivity) above the upper limit of normal (ULN) (reference range for low sensitivity CRP is 3-10 mg/L)
* Subjects must be willing and able, if discharged from the hospital, to return to the hospital or a designated clinic for scheduled visits, treatment, laboratory tests, and other outpatient procedures as required by the protocol.
Exclusion Criteria:
* Treatment with an investigational drug within 30 days preceding the first dose of investigational product.
* Receipt of \> 24 hours of potentially effective IV antibacterial therapy for osteomyelitis within 96 hours of randomization, unless the pathogen isolated was documented to be Methicillin-resistant Staphylococcus aureus (MRSA) that was resistant to the administered antibiotic.
* A prior episode of osteomyelitis, or a failed course of therapy for osteomyelitis.
* Infection associated with a burn wound, with a sacral decubitus ulcer, or with multiple sites of osteomyelitis.
* Septic arthritis that is non-contiguous to osteomyelitis, as diagnosed by isolation of a pathogen from synovial fluid culture.
* Immunosuppression/immune deficiency
* Evidence of Gram-negative bacteria by Gram stain in the absence of Gram-positive organisms.
* Gram-negative bacteremia
* Patients with concomitant endocarditis, necrotizing fasciitis, or prosthetic material at the site of infection at the time of study initiation.
* Infection due to an organism known prior to study entry to not be susceptible to dalbavancin (dalbavancin mean inhibitory concentration \[MIC\] \> 0.25 μg/mL) or vancomycin (vancomycin MIC \> 2 μg/mL).
* Concomitant systemic antibacterial therapy for Gram-positive infections (eg, rifampin, gentamicin).
* Known or suspected hypersensitivity to glycopeptide antibiotics.
* Patients with a rapidly fatal illness, who are not expected to survive for 3 months.
* Pregnant or nursing females; positive urine (or serum) pregnancy test at Screening (pre-menopausal females only) or after admission (prior to dosing)
* Sexually active females of childbearing potential who are unwilling or unable to use an acceptable method of contraception from at least the first dose of study drug until the last pregnancy test.
