The investigators have developed a mobile application (for use on smart phones) to help cancer patients better manage cancer pain. This study is a randomized controlled trial to evaluate the effect of this mobile-based intervention. The investigators' hypothesis is that subjects randomized to the intervention group will have a reduction in pain and pain-related hospitalizations.

Inclusion Criteria:

• All adult patients, 18 years and above suffering from solid-organ cancer.
• Diagnosed with moderate or severe cancer pain (i.e. pain intensity score of at least 4/10 on numeric rating scale (NRS)) at the Massachusetts General Hospital (MGH) Palliative Care Center, as determined by the patient's care provider at the MGH Palliative Care Center. Subjects do not need to experience a specific nature of pain for eligibility.
• Patients must be ambulatory and not currently admitted to the hospital at time of enrollment.
• Must have a smart phone and be willing to download the study application (Phase II only)
• Must be able to read and speak English.

Exclusion Criteria:

• Life expectancy less than 2-months as determined by the palliative care provider
• Significant medical or psychiatric co-morbidities (other than depression or anxiety) or cognitive impediments that would prevent participant from being able to utilize the program
• Known history of substance abuse
• Patients currently on investigational therapies or other study protocols that may have an impact on pain intensity or quality of life which are main outcomes of this intervention.