Based on the perception that a conflict exists between neutrality and agency in Interpreting, this work tries to verify in what ways the concepts of power and ideology inform both the Interpreting Studies and the interpreter’s activity. A multidisciplinary discussion on power and ideology is presented so that the necessary tools are gathered to examine some cases in which one can clearly observe these concepts within the scope of Interpreting. It can be said that different types of fidelity/faithfulness are established according to influences of the environment and their interaction with the values that inform the interpreter in his/her activity. Issues of ethics and control of discourse by interpreters are addressed, putting into perspective the limits of their occupation and encouraging a critical thinking approach to the role of interpreter and the academic studies which have it as their object.