We present the properties of the satellite galaxy population surround the lens HE 0435-1223 as seen through gravitational lensing. From perturbations to the brightness and positions of the lensed images, we infer the likely presence of a satellite near one of the images with total mass log(M) = 9.3 +/- 0.4 M_Sun. Comparison of Bayes factors for our models also implies the possibility of a second satellite with total mass log(M) = 8.8 + 0.5 / -0.8 M_Sun. Using substructure models informed by N-body simulations, we use the image perturbations to study the global population satellites around the lens. Assuming a fixed logarithmic slope of -1.9 and mass range of 10^7 to 10^10 for the substructure mass function, we find the fraction of mass in substructure to > 0.08 % at the Einstein radius of the lens.