The German choral conductor, organist, composer and music pedagogue, Peter Reulein, studied Catholic church music at the Hochschule für Musik und Darstellende Kunst Frankfurt am Main with Wolfgang Schäfer and Uwe Gronostay. After extended studies of organ improvisation with Daniel Roth in Paris, he won several national and international competitions in this field, for example in 1993 the competition of Belgian radio and the second prize and the public's prize at the Festival Europäische Kirchenmusik in Schwäbisch Gmünd. He continued his studies of interpretations with Ludger Lohmann, Ewald Kooiman and Wolfgang Rübsam. He took master-classes with choral conductors such as Eric Ericson and Helmuth Rilling.
From 1991, Peter Reulein was the church musician at the Heilig Geist in Frankfurt-Riederwald, from 2000 he has held the position at Liebfrauen in the centre of Frankfurt. There he directs the Vocalensemble Liebfrauen, the choir Collegium Vocale, the orchestra Collegium Musicum and the youth choir Capuccinis. He was instrumental in having a new organ built which Karl Göckel (de) completed in 2008. He inaugurated the event in a concert on August 9, 2008, playing works by J.S. Bach, César Franck and improvisation.
From 2000 to 2005, Peter Reulein was the head of the Arbeitskreis Kirchenmusik und Jugendseelsorge im Bistum Limburg, caring about more appropriate church music for young people. He has been an instructor of liturgical organ playing and improvisation at the Frankfurt Hochschule für Musik und Darstellende Kunst from 2002. He was appointed Bezirkskantor (de) (regional cantor) for Frankfurt in 2008. In 2014, he recorded at Liebfrauen a CD of Französische Orgelsymphonik (French symphonic organ music) with works by Léon Boëllmann, Camille Saint-Saëns, Alexandre Guilmant and Charles-Marie Widor.
Peter Reulein is known for composing new songs for church services (Neues Geistliches Lied), many of them on texts by Eugen Eckert. He was commissioned to compose an oratorio to celebrate in 2016 the 50th anniversary of church music in the Catholic Diocese of Limburg, presenting different styles of church music. The text by Helmut Schlegel, titled Laudato si' – Ein franziskanisches Magnificat (A Franciscan Magnificat) includes the Latin Magnificat, writings by Francis of Assisi and Clare of Assisi, writings by Pope Francis from the German version of Laudato si' to German, and other sacred texts. He scored the work for five soloists, children's choir, Choralschola, mixed choir, organ and orchestra. It was published by the Dehm-Verlag in Limburg in 2016 and first performed in the Limburg Cathedral on November 6, 2016, conducted by the composer.