Background: A patient’s functional status is a key outcome variable used to both measure and improve quality of care in cancer survivors. However, comprehensive research tools such as the HAQ-DI and WHODAS instruments pose 35 questions altogether, increasing patient reporting burden. We evaluated whether a BLESS could be developed with high sensitivity of screening questions followed by questions relevant to specific physical function domain, through a branching logic algorithm. Methods: Adult cancer clinic outpatients at Princess Margaret Cancer Centre used tablet technology to complete the HAQ-DI, WHODAS, EQ-5D-3L and PRO-ECOG. BLESS was developed as an algorithm that used PRO-ECOG/EQ-5D-3L to screen for appropriate domains of HAQ-DI/WHODAS to query. Sensitivity/specificity of BLESS screeners to HAQ-DI/WHODAS items were reported. BLESS derived physical function scores were also compared to scores generated by the full version of WHODAS/HAQ-DI. Results: Of 407 patients,median age was 62 (range 20-93) years, 51% female, 75% Caucasian, with a median EQ-5D-3L index score of 0.83 (0.31-1.00), and WHODAS of 6.0 (0-37). Of cancer sites, 14% had breast, 11% GI, 11% GU, 18% head/neck, 10% thoracic, 18% hematologic, and 15% gynecologic cancers. 34% were stage III-IV; 72% were treated for curative intent. Using the sum of mobility, self-care, and usual activities dimensions of the EQ-5D-3L to dichotomize patients as with or without difficulty, we found an area under the receiver operating curves that was > 90% when comparing to recommended WHODAS and HAQ cut-offs for significant physical dysfunction. Using BLESS, 38% of our clinic outpatients need answer only 5 questions, generating derived-WHODAS scores with no median difference when compared to reported scores; sensitivity of screeners for each WHODAS/HAQ-DI item ranged from 92-100%. Overall, median number of questions asked was 9. Conclusions: By focusing on relevance, BLESS maintained high sensitivity with a dramatic decrease in question burden compared to traditional research surveys for physical function. BLESS is suitable for use in immediate, routine screening of chronic care outcomes.