The survival rate of women after breast cancer has improved significantly worldwide. More attention should be paid to the rehabilitation intervention after surgery. Cancer rehabilitation helps breast cancer survivors maintain the highest possible physical, social, psychological, and vocational function in the limits that are imposed by the cancer and its treatments. The aim of our research was to determine the rehabilitative setting that promotes greater efficacy of the rehabilitation. A double-blind, randomized controlled trial with 45 patients enrolled was conducted. All participants were randomized into two groups: single rehabilitative training (
N
= 22) and group rehabilitative training (
N
= 23). Outcomes were assessed for each group before treatment (T0), after first 6 weeks of rehabilitative treatment (T1), and after 3 months (T2). All patients underwent the same rehabilitation treatment, but the setting differed between single and group rehabilitative training, which included four to five patients each and evaluated using Minnesota Multiphasic Personality Inventory (MMPI-2), Working Alliance Inventory Patient form (WAIP), Disabilities of Arm, Shoulder and Hand Questionnaire (DASH), and visual analog scale (VAS). Two patients dropped out in the single treatment group. In the within-group analysis at the three evaluation times, on the VAS, a significant reduction in pain was reported and maintained at the follow-up, as was observed for the DASH and WAIP scales. In the between-group analysis WAIP and Bond scale scores differed significantly in favor of the single treatment. In the group treatment, the Psychopathic Deviate, Masculine/Feminine, and Social Discomfort scales of the MMPI-2 correlated with WAIP Tot at T1. There was an association between the Correction, Hysteria, Paranoid, and Schizophrenia MMPI-2 scales and Δ VAS T0T1 in the total sample. Proposing the same rehabilitative intervention in both breast cancer groups, our results showed significant reduction in pain and good functional recovery of the upper limb, which did not depend on the setting (single or group). However, with single rehabilitation treatment, patients developed a better therapeutic alliance and experienced a more comfortable environment.