ImportancePoor prosthetic satisfaction in individuals with upper limb loss has been linked to delayed or nonspecific rehabilitation. The Suitcase Packing Activity (SPA) is a functional outcome measure which has been validated in healthy individuals and assesses bimanual and unilateral upper limb function through a goal-directed task.ObjectiveTo validate the SPA by investigating the relationship between SPA scores and patient-reported outcomes (PROs).DesignCross-sectional cohort study.SettingMilitary treatment facilities, community events, and prosthetic clinics.ParticipantsIndividuals over the age of 18 with major upper limb loss or limb difference who could speak/read English.Outcomes and MeasuresParticipants completed the SPA and questionnaires on patient characteristics, Patient-Reported Outcomes Measurement Information System (PROMIS ® ), and Disabilities of the Arm, Shoulder and Hand (DASH). SPA categories are time, accuracy, and efficiency. Pearson correlations evaluated relationships between SPA subscales and continuous variables. Linear regression determined if DASH score and age could predict SPA scores. Commonality analyses determined the unique, common, and total variance of SPA subscales explained by predictor variables.ResultsTwenty-nine individuals with upper limb loss and limb difference (18 M, age:37.8 ± 12.0, time since amputation:15.7 ± 14.7years) participated in this study. Age, PROMIS ® Social Subscale, and DASH were associated with SPA scores. Age and DASH predicted SPA Time and Efficiency.Conclusions and RelevanceSPA scores align with better PRO scores and demonstrate that the SPA has sufficient concurrent validity to evaluate function in patients with limb loss. Further investigation is warranted to use this measure to compare baseline function or changes over time.