"Guilt" can be defined as remorse for having committed some offense or wrong, real or imagined. It is related to, although distinguishable from "shame", in that the former involves an awareness of causing injury to another, while the latter arises from the consciousness of something dishonorable, improper, or ridiculous, done by oneself. One might feel guilty for having hurt someone, and also ashamed of himself for having done so.
Philip Yancey compares guilt to the sensation of physical pain as an indication that something should not be ignored but attended to. Rabbi David Wolpe says, "Facing up to the hurt we cause others with cruel speech or callous acts, and to our myriad failures to meet the marks God sets for living a true and good life, "makes forgiveness meaningful, not merely a catchphrase,". 
The Penitential Rite at the beginning of the Mass is a liturgical rudiment of this previously sacramental confession. This was discontinued, since for fear of shame it was thought that some might avoid public confession, and private confession became the normal way in which this sacrament was and is practiced, with a strict seal of secrecy on the part of the priest. Sometimes the practice of the sacrament emphasized doing acts of penance, sometimes it emphasized making one's sorrow or contrition authentic, sometimes it emphasized confessing all one's serious (mortal) sins, sometimes it emphasized the power of the priest to absolve the penitent of sin, and currently there are forms that include simply one-on-one confession to a priest or communal preparation and then one-on-one confession to a priest.
Guilt is an important factor in perpetuating Obsessive–compulsive disorder symptoms. Research is mixed on the possible connection between Catholicism and obsessive-compulsive symptoms. A study of 165 individuals by the University of Parma found that religious individuals scored higher on measures of control of thoughts and overimportance of thoughts, and that these measures were associated with obsessive-compulsive symptoms only in the religious participants. Another study noted a link between intrinsic religiosity and obsessive-compulsive cognitions/behaviors only among Catholic participants. However, a study from Boston University found that no particular religion was more common among OCD patients, and that OCD patients were no more religious than other subjects with anxiety. Religious obsessions were connected to the participants' religiosity, but sexual and aggressive symptoms were not. Greater religious devotion among OCD patients was correlated with increased guilt.
A study in American Behavioral Scientist analyzed interviews with participants from Catholic, Jewish, and Protestant backgrounds. The author reported that most participants "eagerly described an experience of guilt." 
University of Ulster students participated in a study that found a slightly higher level of collective guilt among the Catholic students than the Protestant students.
Researchers from the University of California at Berkeley and from the University of Notre Dame examined the concept of Catholic guilt among U.S. teenagers. The authors found no evidence of Catholic guilt in this population, noting that Catholicism both caused and relieved less guilt than other religious traditions. The authors found no evidence that Catholic teenagers experience more guilt than non-Catholic teenagers. The authors did not find that more observant Catholics feel guiltier than less observant Catholics. The study also noted no difference in the effect of guilt-inducing behaviors on Catholic versus non-Catholic participants.
A study from Hofstra University reported no difference in total guilt among religions, although religiosity itself was connected to guilt.
Guilt can be viewed in terms of constructiveness versus destructiveness: "constructive guilt" is focused on forgiving one's ethical lapses and changing one's behavior, while "destructive guilt" remains mired in self-loathing and does not emphasize learning from one's wrongdoings and moving ahead with life. A study in Psychology of Religion found that Catholic participants demonstrated a higher level of constructive guilt reactions than other groups.
Living in sin, with sin, by sin, for sin, every hour, every day, year in, year out. Waking up with sin in the morning, seeing the curtains drawn on sin, bathing it, dressing it, clipping diamonds to it, feeding it, showing it round, giving it a good time, putting it to sleep at night with a tablet of Dial if it's fretful. Always the same, like an idiot child carefully nursed, guarded from the world. 'Poor Julia,' they say, 'she can't go out. She's got to take care of her little sin. A pity it ever lived,' they say, 'but it's so strong. Children like that always are. Julia's so good to her little, mad sin.’ 
Jack Donaghy: That's not how it works, Tracy. Even though there is the whole confession thing, that's no free pass, because there is a crushing guilt that comes with being a Catholic. Whether things are good or bad or you're simply... eating tacos in the park, there is always the crushing guilt".
- Stravinskas, Peter (1990). Catholic Answer Book. Our Sunday Visitor. p. 78. ISBN 0-87973-458-2.
- "Simple definition of 'Guilt'", Merriam-Webster's Learner's Dictionary
- Burgo, Joseph. "The Difference Between Guilt and Shame", Psychology Today, May 30, 2013
- Grossman, Cathy Lynn. "'Catholic guilt,' 'Jewish guilt' not just a joke, it's essential", USA Today, October 14, 2010
- Gula, Richard M. (1984-05-01). To Walk Together Again: The Sacrament of Reconciliation. Paulist Press. ISBN 978-0-8091-2603-3.
- Leslie J. Shapiro, LICSW. "Pathological guilt: A persistent yet overlooked treatment factor in obsessive-compulsive disorder —". Aacp.com. Retrieved 2013-11-02.
- Sica, Claudio; Novara, Caterina; Sanavio, Ezio (2002-07-31). "Religiousness and obsessive–compulsive cognitions and symptoms in an Italian population". Behaviour Research and Therapy. 40 (7): 813–823. doi:10.1016/S0005-7967(01)00120-6. PMID 12074375. Retrieved 2013-11-02.
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- Collective Guilt: International Perspectives – Google Books. Books.google.com. 2004-09-06. ISBN 978-0-521-52083-6. Retrieved 2013-11-02.
- Vaisey, Stephen; Smith, Christian (1 January 2008). "Catholic Guilt among U.S. Teenagers: A Research Note". Review of Religious Research. 49 (4): 415–426. doi:10.2307/20447515 (inactive 2016-08-19). JSTOR 20447515.
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- IMDB 30 Rock
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- Mallon, John (April 2006). "The Primacy of Jesus, the Primacy of Love". Inside the Vatican. Retrieved 2006-11-01.
- Hill, James (April 2012). "My First Visit to a Non-Catholic Church". Christians for Christ Web Site. Christians for Christ Ministries. Retrieved May 2012. Check date values in: