This article addresses the distinction of West Bengal Sign Language (WBSL), from the Delhi variety of the Indian Sign Language (ISL) within the Indian subcontinent, and the relationship of WBSL to Bangla Sign Language (BsSL) of Bangladesh. Both WBSL and BaSL are the names given by their respective Deaf communities. This article is the result of our research on these signed language varieties, made over the course of twelve years (seven of which were spent in Kolkata [formerly Calcutta], West Bengal) while working among Deaf people in India. Data collected in Bangladesh was also used. Our observations of a different signed language in West Bengal and the impact of researcher bias (also known as the Observer’s Paradox), as well as a high level of exposure to wider India’s signed languages among fluent Deaf signers, prompted this research. Sign languages acquired from other Deaf communities in India and previous claims of the existence of only one signed language in India necessitated the inclusion of several language components (lexicon, intelligibility, identity, anecdotal evidence) and statistical analysis in the differentiation of WBSL from ISL, in particular, the Delhi variety. Results of the statistical analysis show that WBSL is different from the Delhi variety of ISL.