For those randomized to a cohort with the Valera app, the app (and cellphones if necessary) will be provided. The app is Health Insurance Portability and Accountability Act (HIPAA) compliant and Institutional Review Board (IRB) approved. It consists of 2 components: a participant-facing Smartphone Application and a corresponding online Care Manager Dashboard. Smartphones and internet access will be provided as needed for the 12-week study duration.

TAU for Buprenorphine (BUP) treatment typically consists of regularly scheduled visits every 1-2 months with primary care physicians and/or nurse care managers in Montefiore primary care settings. During these 15-min follow up visits, providers typically inquire about opioid and other substance use, opioid craving, symptoms of opioid withdrawal, and risk of relapse. In addition, at each visit, urine toxicology tests are conducted and providers review results of prior urine toxicology tests with patients. If opioid or other substance use is ongoing, typically providers will intensify treatment, including increasing the frequency of visits, referring to social workers or mental health providers, recommending self-help groups, and/or recommending outpatient drug treatment programs (e.g., individual and group counseling).

Psychological inflexibility is measured using the Multidimensional Psychological Flexibility Inventory - Short (MPFI-S) inflexibility scale, which consists of 12 items. Responses range from 1 ("Never true") to 6 ("Always true"). There are two subscales measuring psychological flexibility and inflexibility across key areas. A global composite score for inflexibility uses the last 12 answers and divides scores by 12 to obtain a mean score. Higher scores reflect higher levels of psychological inflexibility.

Psychological inflexibility related to substance use is measured using the Acceptance and Action Questionnaire-Substance Abuse (AAQ-SA), a self-report scale. The AAQ-SA assesses the degree to which individuals avoid or struggle with substance-related thoughts, urges, and emotions, and the extent to which these experiences interfere with values-consistent behavior over recent weeks. Items are rated on a 7-point Likert scale ranging from 1 ("Never true") to 7 ("Always true"). Several items are reverse scored so that item responses can be summed to yield a total score, with lower scores indicating greater psychological flexibility (i.e., less experiential avoidance) in the context of substance use.

Committed action is measured using the Committed Action Questionnaire (CAQ), an 18-item self-report scale. Each item assesses the degree to which individuals persist in values-directed actions in the face of discomfort over the past several weeks and is rated on a 7-point scale ranging from 0 ("Never true") to 6 ("Always true"). Item scores are summed to produce a total score ranging from 0 to 108, with higher scores indicating greater levels of committed action.

Pain acceptance is measured using a 20-item scale called the Chronic Pain Acceptance Questionnaire--Revised (CPAQ-R). This is designed to measure acceptance of pain. It is measured on a scale of 0 ("Never true") to 6 ("Always true"). There are two subscales: (1) activity engagement, (2) pain willingness. Total score for pain acceptance is derived from mean scores on each of the subscales. Higher scores indicate higher levels of acceptance.

Pain catastrophizing is assessed via the 6-item Pain Catastrophizing Scale (PCS-6). The PCS-6 is a shortened version of the full 13-item Pain Catastrophizing Scale, designed to assess pain-related catastrophic thinking. Each items assesses maladaptive, cognitive, and emotional responses to pain experiences. Responses to items 4, 5, 6, 10, 11, and 13 from the original 13 item scale are rated on a 5-point scale ranging from 0 ("Not al all") to 4 ("All the time"). Item scores are summed to produce a total score ranging from 0-24, with higher scores indicating greater levels of pain catastrophizing. Scores will be summarized by study arm using basic descriptive statistics.

Change in pain intensity on average over the prior 7-day period will be assessed using the Brief Pain Inventory (BPI) pain intensity subscale. The BPI pain intensity subscale consists of 4 items which asks patients to rate their worst pain, least pain, average pain, and current pain using a 0-10 numeric rating scale (NRS), where 0 represents "No pain" and 10 represents "Pain as bad as you can imagine," such that higher scores are associated with greater pain intensity. Scores from the four items are averaged to obtain a mean score. Results will be summarized by study arm using basic descriptive statistics.

Heroin use will be defined by self-reported heroin use days of the past 30 days using an item from a modified Addiction Severity Index questionnaire. The possible range of days is 0-30. Results will be summarized by study arm using basic descriptive statistics.

Fentanyl use will be defined by self-reported fentanyl use days of the past 30 days that is not prescribed, using items from a modified Addiction Severity Index questionnaire. The possible range of days is 0-30. Results will be summarized by study arm using basic descriptive statistics.

Prescription opioid analgesic use will be defined by self-reported number of days of prescription opioid analgesic use that is not prescribed, over the past 30 days, using items from a modified Addiction Severity Index questionnaire. The possible range of days is 0-30. Results will be summarized by study arm using basic descriptive statistics.

HRQoL will be assessed using a utility score from the Patient-Reported Outcomes Measurement Information System (PROMIS)-Preference (PROPr) scoring system. PROPr summarizes several PROMIS domains into a single, preference-based score. PROPr is a health utility score which aggregates scores from 7 PROMIS domains: Cognitive Function/Abilities, Depression, Fatigue, Pain Interference, Physical Function, Sleep Disturbance, and Ability to Participate in Social Roles and Activities. PROPr scores are calculated using a multiplicative multiattribute utility function that combines the individual PROMIS domain scores into a single score. The PROPr score is expressed as a health utility index value on a scale between 0 (the utility of being dead) and 1 (utility of full health) such that higher scores are indicative of better perceived overall health utility. Scores will be summarized by study arm using basic descriptive statistics.

Global Impression of change from the beginning of the study will be evaluated using the Patient Global Impression of Change (PGIC) assessment. The PGIC consists of a single item which asks the participant "Since the start of the study (treatment), my overall pain is..." and asks the participant to rate their pain on a 7-point Likert scale ranging from 0 ("Very much improved") to 6 ("Very much worse"), such that lower scores are associated with an overall impression of improvement since the start of the study. Results will be summarized by study arm using basic descriptive statistics.

Depressive symptoms are measured using the Beck Depression Inventory (BDI), a 21-item self-report scale. Each item assesses the severity of a depressive symptom experienced over the past two weeks and is scored on a 4-point scale ranging from 0 ("Symptom not present") to 3 ("Severe symptom"). Item scores are summed to produce a total score ranging from 0 to 63, with higher scores indicating greater severity of depressive symptoms. Scores will be summarized by study arm using basic descriptive statistics.

Anxiety symptoms are measured using the Beck Anxiety Inventory (BAI), a 21-item self-report scale. Each item assesses the severity of common anxiety symptoms experienced over the past week and is scored on a 4-point scale ranging from 0 ("Not at all") to 3 ("Severely; it bothered me a lot"). Item scores are summed to produce a total score ranging from 0 to 63, with higher scores indicating greater severity of anxiety symptoms. Scores will be summarized by study arm using basic descriptive statistics.

Positive urine for non-prescribed opioids will be assessed using point of care urine drug testing. Results of the test will be reported using a dichotomous variable ("Yes"/"No") where "Yes" is is indicated by positive oxycodone, fentanyl, or other opiates that were not indicated by participant as prescribed.

Anhedonia will be assessed via the Snaith-Hamilton Pleasure Scale (SHAPS), a 14-item self-report scale. Each item assesses the ability to experience pleasure over the past few days and is rated on a 4-point scale consisting of "Strongly disagree," "Disagree", "Agree," or "Strongly agree". For scoring, responses will be dichotomized such that "Strongly disagree" and "Disagree" are scored as 1 point and "Strongly agree" and "Agree" are scored as 0 points. Scores are summed to yield a total score ranging from 0 to 14. Higher total scores indicate greater levels of anhedonia.

Psychiatric diagnoses are assessed using the Mini International Neuropsychiatric Interview (MINI), a structured diagnostic interview based on Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria. The MINI is administered by trained study personnel to determine the presence or absence of current psychiatric disorders. Diagnoses are assessed at multiple time points to evaluate changes in diagnostic status over the course of the study. The total number of diagnoses at each timepoint will be reported. A higher number reflects higher burden of psychiatric disease.

Retention with buprenorphine will be measured by a dichotomous measure of whether a buprenorphine prescription occurred within 1 week of the time of a study visit. This is measured using pharmacy data obtained through I-stop, a NY State controlled substance monitoring program. Results will be summarized by study arm.

For participants enrolled into the ACT arm, satisfaction with ACT is measured using the Satisfaction With Therapy Scale (STS), a 14-item self-report questionnaire. The scale assesses participants' satisfaction with various aspects of their therapeutic experience. Each item is rated on a 5-point Likert scale ranging from 1 to 5, and item responses are summed to yield a total score ranging from 14-70. Higher total scores indicate greater satisfaction with ACT.

For participants enrolled into one of the Valera smartphone application arms, satisfaction with Valera is measured is measured using a novel scale measuring overall satisfaction along with satisfaction with three different components: (1) Educational articles, (2) Appointment Reminders, and (3) Messaging Care Team. Each is measured along a Likert-type scale from 1-5, with higher scores reflecting higher satisfaction or usefulness, of Valera.

For participants enrolled into one of the Valera smartphone application arms, Valera Engagement with articles is a dichotomous measure assessing whether participants opened up each of 24 articles sent to participants twice weekly across the 12 week intervention. Each measure is measured as "Yes" or "No." Total engagement will be reflected as a percentage of total yes answers over the 24 articles. Higher percentages reflect higher engagement with articles.

For participants enrolled into the ACT arm, ACT attendance is a measure of attendance of each of 12 ACT sessions. These will be reported as percentages. Higher percentages indicates higher attendance.