The Sustainable Livelihood Security Index (SLSI) as a multidimensional framework is designed to assess livelihood resilience integrating economic, environmental, social, and cultural dimensions. This study explores the conceptual foundations, methodology, and applications of SLSI, emphasizing its role in rural development, poverty alleviation, and climate adaptation. Using Dunda Village in Uttarakhand, India, as a case study, the research employs Participatory Rural Appraisal (PRA) and secondary data to evaluate livelihood security through normalized and weighted indicators. Results reveal a moderate aggregate SLSI score (0.53 and 0.54), with strengths in literacy, electricity access, and biodiversity, but weaknesses in income, healthcare, and gender equality. Statistical analysis (paired t-test) confirms no significant difference between equal and expert weighting methods, underscoring methodological robustness. The study highlights SLSI’s utility in identifying vulnerabilities and informing targeted interventions, while also addressing limitations such as data quality and contextual relevance. Comparative analysis with global frameworks such as HDI and EPI underscores SLSI’s holistic approach, particularly its inclusion of cultural sustainability rarity in existing indices. Future research directions call for dynamic indicators and enhanced local adaptability to improve policy relevance. This study contributes to the discourse on sustainable livelihoods by offering a scalable tool for assessing and enhancing resilience in resource-dependent communities.