Larval and adult stages of marine species with complex life cycles often differ in their thermal tolerance, with larvae typically showing narrower limits. To assess how such stage-specific differences may influence species' range dynamics under climate change, we quantified larval performance of the European shore crab Carcinus maenas across an environmental temperature gradient. We measured larval survival rates (%) from hatching to metamorphosis to megalopa, duration of development (days), and growth (day-1) at seven constant temperature treatments (9-27 °C, in 3 °C increments). Data represent experimental observations of larval performance under laboratory conditions and are reported at the level of replicates by females of each population. Replication was performed on two levels: 5 * 10 larvae were reared per female, and 4 to 6 females were used per population. Larvae were collected from populations at the southern and northern parts of the native European distribution (Vigo, Spain; Bergen and Trondheim, Norway). The data were collected during one reproductive period in 2022. We aimed to test the hypothesis that larvae from northern populations are more tolerant to low temperatures, while southern populations exhibit increased tolerance to high temperatures, which would facilitate poleward range expansion under warming conditions.Our results show that larvae from Spain displayed slightly higher survival rates to megalopa at warmer temperatures compared to those from northern populations. However, little variation in tolerance was observed between northern Spain and Norway, with low survival and growth at the temperature extremes (9 °C and 27 °C). Notably, larvae from Norway exhibited faster development at low temperatures, which may represent an adaptive response to local thermal conditions. These findings suggest that future shifts in the distribution of C. maenas are most likely to be driven by rising temperatures, unless populations at the range edges evolve enhanced tolerance to thermal extremes.