Introduction: Aphasia impacts language and thought organisation, disrupting effective communication. Thought, Language, and Communication (TLC) are interrelated, and breakdown in one domain often affect the others. A comprehensive assessment tool is essential to understand and address these interlinks. This study aims to develop and preliminarily validate the TLCAS-PWA for Tamil-speaking PWA and to compare it with NTI. Methods: The tool was developed through literature review and expert validation, comprising 14 parameters across communication, language, and thought domains, rated on a 5-point scale. It was administered to 20 PWA and 20 NTI. Results: Among PWA, PCS showed the highest mean scores, while SR was the least frequent. At the domain level, both PWA and NTI had higher scores in Communication Disorder and lower scores in Language Disorder. Mann-Whitney U tests revealed significant differences between groups across all the domains. Psychometric analysis showed good internal consistency (α = 0.88) and excellent inter-rater reliability (ICC = 0.98, 95% CI: 0.88-0.99). The test–retest reliability (ICC) showed excellent reliability for the communication and Thought domain and good for the Language domain. Conclusion: TLCAS-PWA is a preliminarily validated tool that aids clinicians in assessing TLC, supporting diagnosis in PWA. © 2025 Lakshmipriya, S.M., Hema, N.