Remotely-Delivered Cognitive Behavioral Stress Management Effects on Cancer-Accelerated Aging in Older, Distressed Breast Cancer Survivors - Protocol Synopsis-Brief Summary Study Overview. We will enroll Breast Cancer Survivors (BCS) who completed initial treatment within 3 – 12 months which may or may not have included chemotherapy, are continuing on adjuvant endocrine therapy (AET), who are distressed, mid-older aged (> 50yrs), post- menopausal, and were diagnosed with Stage I – III HR+ (ER/PR+), Her2neu- breast cancer. We will have a brief run-in period starting just after treatment completion (i.e., waiting period prior to randomization) where potentially eligible participants will undergo screening. At least 3 months and up to 12 months after the completion of initial treatment they will be asked to complete a baseline assessment over REDCAP, collect saliva samples over 2 consecutive days (4 times daily) in the same week to assess Area Under the Curve (AUC) and diurnal salivary cortisol slopes, wear an Empatica wristband to collect heart rate variability (HRV) to index parasympathetic nervous system activity, and attend an in-person visit for blood draw. A total of 192 participants who complete the run-in period will be block randomized (on the basis of receiving or not receiving chemotherapy) to receive either: 1) Remotely-delivered Cognitive Behavioral Stress Management (R-CBSM) + Survivorship Care Planning (SCP) (n = 96); or 2) SCP-only control (n = 96). After randomization, participants assigned to R-CBSM+SCP receive a link to attend 10 weekly group R-CBSM sessions by ZOOM and are provided access to a website containing education materials corresponding to stress management modules. During the intent-to-treat period, we monitor weekly changes in intervention processes (stress, mood, perceived stress management skills, emotion regulation) via ecological momentary assessment (EMA) to mobile phones or will use paper diary. After the interventions are completed follow-up assessments at 6 and 12 months are completed via RedCap questionnaires, saliva (cortisol), wristbands (for HRV) and blood (immune measures) to characterize intermediary improvements in psychological adaptation, and neuroimmune regulation. Participants are also assessed for physical (longer-term immune cell senescence) and mental health (depression, quality of life) over 0, 6, 12 and 24 months with questionnaires or interviews (remote or in-person), and blood draws. In total they will complete 4 visits (T1: 0m, T2: 6m, T3:12m, T4: 24m) as well as remote intercurrent monitoring of intervention processes over the 0- 3 month training period for both the R-CBSM+SCP and SCP-only conditions. Monitoring intervention process changes will be a manipulation check and will inform whether these changes are specific to R-CBSM and whether they are correlated with changes in intermediary regulatory variables.