A computational method to reconstruct full-length, paired T cell receptor (TCR) sequences from T lymphocyte single-cell RNA sequence data. TraCeR links T cell specificity with functional response by revealing clonal relationships between cells alongside their transcriptional profiles. TraCeR extracts TCR-derived sequencing reads for each cell by alignment against ‘combinatorial recombinomes’ comprising all possible combinations of V and J segments. Reads are then assembled into contiguous sequences that are analyzed to find full-length, recombined TCR sequences. Importantly, the reconstructed recombinant sequences typically contain nearly the complete length of the TCR V(D)J region and so allow high-confidence discrimination between closely related gene segments. Our method is sensitive, accurate and easy to adapt to any species for which annotated TCR gene sequences are available.