Testimony to integrity and truth, refers to the way many members of the Religious Society of Friends (Quakers) testify or bear witness to their belief that one should live a life that is true to God, true to oneself, and true to others. To Friends, the concept of integrity includes personal wholeness and consistency as well as honesty and fair dealings. From personal and inward integrity flow the outward signs of integrity, which include honesty and fairness. It is not only about telling the truth - it is applying ultimate truth to each situation. For example, Friends (Quakers) do not believe that one should trick others by making statements that are technically true but misleading.

The word testimony is used to refer to the ways in which Friends testify or bear witness to their faith in their everyday lives. In this context, the word testimony refers not to Friends' underlying beliefs about truth and integrity, but their committed action to promote and act in truthful and integral ways, which arises out of their beliefs.

Also known as the Testimony of Truth, or Truth Testimony, the essence of the Testimony of Integrity is placing God at the center of one's life. To Friends, integrity is in choosing to follow the leading of the Spirit despite the challenges and urges to do otherwise.

This testimony has led to Friends having a reputation for being honest and fair in their dealings with others. It has led them to give proper credit to others for their contributions and to accept responsibility for their own actions. In those legal systems where it is allowed, rather than swearing oaths in a court of law Friends will prefer to affirm — in England this has been the case since 1695.

Among some early Friends this testimony led them to refuse to participate in drama, stating that to pretend they were someone else was to deny their integrity.