The red spiny lobster, Panulirus penicillatus (Olivier, 1791), is exploited commercially in the Galápagos Marine Reserve by the local fishing sector. Catches and catch per unit effort have declined over the past few years, leading to concerns about sustainability of the fishery. This study supports the processes regarding the fishery management of P. penicillatus by determining its distribution and growth parameters. Nearly 3,000 lobsters were tagged during surveys carried out at 13 islands between 2000 and 2004. Sex ratio did not differ significantly from 1:1, and tagging returns showed little or no movement of individuals. Mean values with 95% confidence intervals for von Bertalanffy growth parameters were estimated to be K = 0.201 ± 0.004, L_∞ = 16.91 ± 0.183 (cm carapace length), and Φ′ = 4.14 ± 0.019 for males; and K = 0.264 ± 0.02, L_∞ = 12.34 ± 0.40 (cm carapace length), and Φ′ = 4.99 ± 0.06 for females. Natural mortality was 0.342 for males and 0.378 for females. These results, together with comparative estimates for red spiny lobster elsewhere, illustrate the geographical variability of growth among populations of P. penicillatus, which may occur within the archipelago itself.