ctmm is an R package for analyzing animal tracking data as a continuous-time stochastic processes. Package features include FFT variogram and Lomb-Scargle periodogram analysis, Kalman-filter maximum-likelihood estimation, Kriging, simulation, and autocorrelated kernel-density home-range estimation. First-time users can start with the Methods in Ecology and Evolution paper and then move on to the up-to-date vignettes vignette('variogram') and vignette('akde').