Expert: Michael Clark, Ph.D. - 12/3/2007

Question
Is masturbating a mortal sin for young people to be doing, it says that it is a sin to be doing, but then says stuff about physiological and other things like that that diminish the sin and not being mortal sin, I am just confused about it.

thanks

Answer
You're right it does say all that:

2352 By masturbation is to be understood the deliberate stimulation of the genital organs in order to derive sexual pleasure. "Both the Magisterium of the Church, in the course of a constant tradition, and the moral sense of the faithful have been in no doubt and have firmly maintained that masturbation is an intrinsically and gravely disordered action." "The deliberate use of the sexual faculty, for whatever reason, outside of marriage is essentially contrary to its purpose." For here sexual pleasure is sought outside of "the sexual relationship which is demanded by the moral order and in which the total meaning of mutual self-giving and human procreation in the context of true love is achieved."
To form an equitable judgment about the subjects' moral responsibility and to guide pastoral action, one must take into account the affective immaturity, force of acquired habit, conditions of anxiety or other psychological or social factors that lessen, if not even reduce to a minimum, moral culpability.

Source: http://www.scborromeo.org/ccc/para/2352.htm

I think what the Church might be saying is that it's sometimes challenging for people not to masturbate, and for various reasons. And God is a loving God and would understand all that.