Gregorian Chant（格林高利圣歌）是在罗马天主教会的正式礼拜仪式中所唱的圣歌，起源于中世纪的罗马天主教会。当时有位教宗叫格林高利一世（Gregorius Magnus，公元590-604任职），他曾将这些圣歌编辑成册，因此后世人称其为Gregorian Chant。Gregorian Chant具有以下特征：歌词全是拉丁文，是无伴奏、无和声的单一旋律线，节奏非常自由，采用不同于“大小调系统”的调式音阶，同时还具有客观的、非个人的与超世俗的性质。这种圣歌音乐与礼拜仪式密不可分，它们可算是“功能性的音乐”，亦即具有特殊功用的音乐，不具娱乐价值。它们主要旨在表达歌词的宗教内涵，而不注重官能美感或情感诉求。但有趣的是，中世纪许多俗乐与民谣却改编自Gregorian Chant的曲调。
圣乐对中世纪的欧洲人而言，与日常生活息息相关。当时，社区的每一份子都必须参加宗教聚会，并在聚会中唱圣歌。天主教的主要礼拜仪式有两种：“弥撒”与“日课经文”，Gregorian Chant就是应用在这两种天主教的礼仪歌曲。例如，弥撒常用部分的歌曲包括《垂怜曲》或《慈悲经》、《光荣颂》或《荣耀经》、《信经》、《欢呼歌》或《圣哉经》、《羔羊赞》，在中世纪时都是用Gregorian Chant来吟唱。因此一般民众对于Gregorian Chant的熟悉程度就如同今日一般民众对于本地流行歌曲的熟悉程度。
Gregorian Chant只用人声，没有和声和对位，旋律简单，不用变化音和装饰音，音域也很窄，一般不超过八度。虽然它的旋律没有明显的节奏重音，速度徐缓，但较好地配合了拉丁文歌词的抑扬顿挫。Gregorian Chant 在产生、发展过程中，吸收了古希腊、希伯莱、叙利亚和巴勒斯坦地区的音乐，因此，它使我们了解了已失传的古代地中海地区的音乐文化。
Originally, Gregorian was conceived as a more pop-oriented group in the vein of Enigma. Under this concept, they recorded the 1991 album Sadisfaction, with lead vocals provided by The Sisters of Oz: Susana Espelleta (Peterson's wife at the time) and Birgit Freud. However, this was the only album in that style.
In 1998, Peterson and his team Jan-Eric Kohrs, Michael Soltau and Carsten Heusmann re-invented the project to perform popular songs in the Gregorian style. The criteria for song selection were strict; in order to be considered, a song needed to be translatable into the 7-tone scale. For each album, songs were carefully chosen in addition to original songs written by Jan-Eric Kohrs, Amelia Brightman and Carsten Heussman. Twelve vocalists - previously acclaimed session and choir singers - were then hired to record the tracks.
Each Gregorian album is initially digitally tracked at Nemo Studios, Peterson's Hamburg studio. The vocalists then record their parts in a church atmosphere with dimmed lights and candles, in order to escape what Peterson referred to in a 2001 interview as the "cold and technical" studio atmosphere.
The concept proved to be successful, and the group proceeded to record several more Masters of Chant albums in the same style. Their 2004 album, The Dark Side, was a slight departure from the others, featuring a darker repertoire consistent with the title.
In 2005, The Masterpieces, a compilation album with a live DVD, was released. A fifth Masters of Chant album was released on 31 March 2006. In 2006, a festive album was also released, titled Christmas Chants. A sixth Masters of Chant album was released on 28 September 2007. In 2009 a seventh Masters of Chant album followed.
Gregorian in 2009On 8 September 2010 the next album, titled The Dark Side of Chant, was announced to be published on 15 October 2010.
The members of the Gregorian choir group are Richard Naxton (Naxos), Johnny Clucas (Johnny), Chris Tickner (Chris T.), Richard Collier (Rich), Gerry O'Beirne (Gerry), Lawrence White (Lorro) and Rob Fardell (Rob F.).
Others who contribute to the vocals or sound of Gregorian are Sarah Brightman (under the pseudonyms Hepsibah or Sarah Hellmann), Amelia Brightman (Sarah Brightman's younger sister), Frank Peterson, and staff of Nemo Studio among others.
01. So Sad
02. Nothing Else Matters
03. Moment of Peace
04. Voyage Voyage
06. Join Me(Schiller Version)
07. The Raven
09. The Forest
10. Fix You
12. Happy X-Mas(War is Over)
14. Forever Young
16. Let Down
18. Crazy Crazy Nights