[en] We present a study of the entanglement of formation for one-dimensional magnetic systems with defects. The concurrence was used as a measure of entanglement. Rather than locating the impurity at one site in the chain, there is a Gaussian distribution of disorder near a particular location. We demonstrate that the entanglement can be tuned by varying the strength of the external magnetic field and the distribution of impurities. The concurrence is a maximum close to the critical point, where a quantum phase transition occurs, and for certain parameters can be tuned to zero above the critical point