This Guide is the result of my experience of searching free classical sheet music on the net. If  you are looking for a specific classical sheetmusic and cant find it in my list or in the list of directories, I'll try to help you, just send  me a mail.
Hundred of sites offer free classical downloadable sheet music on the net but  few are satisfactory.I have selected a few sites where you will find your way easily. All sheetmusic are in the public domain and therefore free and legal. Make sure, you have the right software to view and print the music scores.
My Selection of Sites
210 000 scores !..... A real Must
IMSLP attempts to create a virtual library containing all public domain musical scores, as well as scores from composers who are willing to share their music with the world without charge.IMSLP has more than 26 000 scores
On Line Musical Scores (William and Gayle Cook Music Library)
Catalog of music from Indiana University The best."Scores of all kinds, from opera, to orchestral, choral, piano and more. To download scores, select the category you want, and then when you find the score you want, view the 'larger, scrollable version' of each. This will open your browser into a new window, from which you can scroll through each page of the sheet music. *.Gif format, and you'll need to right click on each image to save each page to your local drive." Review from the Free Sheet music guide
Choral Public Domain Library
The Choral Public Domain Library (CPDL) is the largest website devoted exclusively to free choral sheet music.
14 000 public domain choral works most in PDF, finale, or MIDI format. Bach, Brahms, Mozart, Purcell and choral music from earlier composers such as John Bartlet, William Byrd, Josquin, John Dowland, & Thomas Morley.
University of Rochester Sheet Music Library
All legal PDF, wonderful
Free Sheet Music Library
Great Collection : Orchestra Work, Chamber Music , Piano Work, Organ work , sacred Work (Bach) Had seemingly disappeared from the web but welcome back. PDF

Werner Icking Music Archive

This site continues  the GMD Music Archives
Large collection of classical and contemporary scores for: Piano, Violin, Cello, Viola, Voice, Choral, Organ, Flute, Classical Guitar.PDF or PostScript format.If you do not have a Postcrip printer , use  Ghostscript, Ghostview & GSview .
1256 Free scores PDF
Metronimo
895 free scores PDF on this french site Well designed and easy to use
Rowy.net
PDF, largest non-commercial sites with free sheet music for solo music instruments . Excellent site.More than 2000 scores
Musicologie
Lots of Free Scores and midi by Jean-Marc Warszawski
Mutopia
Mutopia is ran  by volonteers. 1727 collection of Postscript (.ps) and PDF files as well as Lilypond's own LY (.ly) file format. Modern editions, arrangements and new music
Free-Scores.com
38935 files PDF and midi to download on this sheet music directory
Sheet Music Fox
Lots of Free Scores PDF
Digital Mozart Edition
The purpose of this web site operated by the Internationale Stiftung Mozarteum in cooperation with the Packard Humanities Institute is to make Wolfgang Amadeus Mozart's musical compositions widely and conveniently accessible to the public, for personal study and for educational and classroom use.
Chopin
See this Guide section for Chopin Free sheet music
 
These sites have a smaller collection.or a more specialized collection of free sheetmusic
More Sites
Acadia Early Music Archives
PDF
All Piano Sheet Music
Freedownload section at the end of the first page.Many free classical Piano sheet music files to download
Anyscores.com
Very small collection (9) PDF
ARIA Data Base
Collection of information on over 1000 operatic arias. Designed for singers and non-singers alike, the Database includes translations and aria texts of most arias as well as a collection of MIDI files of operatic arias and ensembles
CCARH Publications Bach and Vivaldi
Bach, Handel, Mozart and Vivaldi PDF
Score/Parts for J.S. Bach, BWV 11 (Cantata). Score/Parts for J.S. Bach, BWV 43 (Cantata). Score/Parts for J.S. Bach, BWV 48 (Cantata).
Parts for Vivaldi, Op.8 concerti grossi.
Bach Scores of Bach Cantatas & Other Vocal Works
Scores of Bach Cantatas & Other Vocal Works -Bach Cantata BWV 1 -224 all free.A fantastic site
Great Bach
All JS Bach's Works in PDF and midi.
Great collection of Brass music
The Hector Berlioz web site
A fantastic non profit site devoted to Berlioz music with free partitions Scorch plug ing needed.
Calm-Down-Corner
Piano sheet music for intermediate to advanced level for free download. The short pieces offer a change from the classical teaching material and are also suitable for keyboard
Capotasto Music

Free printable sheet music for guitar, bass guitar, piano, flute, clarinet, violin, alto saxophone, tenor saxophone, trumpet, cello, ukulele and recorder. Easy Piano, classical piano, easy piano lesson scores. Free Christmas sheet music Free sheet music for piano including Auld Lang Syne, Fur Elise, Happy Birthday To You, O Christmas Tree, House Of The Rising Sun and Love Me Tender.

Cantorion.org  
Cantate Domino Church and choral music. We hope to provide a growing collection of Anthems and Motets, Services and Settings, Hymns and Psalms, Organ and piano music, and a large selection of carols.
The Clarinet Institute of Los Angeles
Free Sheet Music for Clarinet PDF
Cipoo      
1951 Free domain public Choral sheet music
Copy us internet music publishing
Publishes the works of composers free of charge via the internet. All the 480 scores are free for download and high quality PDF format.New : 133 scores for piano education:
A Database of Vocal music of the french Renaissance  
PDF
Delcamp.net
A very nice classical Guitar site .Delcamp.net is a resource center and meeting place for classical guitarists from around the world. 2546 pages of Classical Guitar sheet music
Douglas Yeo
PDF Cello scores
Dotsfor strings Free sheet music for string quartet
Jacques Duphly 1715-1789
Sheet music for Harpsichord (scanned) French composer XVIII century
Easy Sheet music

70 pages of the most popular Classical pieces for easy Piano. Learn to play the great works of Tchaikovsky, Mozart, Chopin and many others.Boogies, World songs operas
3 free downloads per day

Edumus.com
PDF winzip
8notes.com
This site has recently changed its policy for free sheet music and introduced a membership right. But it has a few free scores coming from other sites
 
Free Classical Sheet Music
The emphasis of this site is on complete Piano albums with music in an easy or intermediate playing level
Free Sheetmusic from Johan Tuvesson
Modern editions of a lot of music from the 17:th and 18:th century for Strings
Free sheet Music The list starts with "First Pieces" which you barely need to know how to read sheet music to play. From there, you move up to the "Primer Level" and then Levels 1-4 and "Keyboard Classics." You'll know virtually every song on this site, which contains lots of popular "traditional" tunes (Bridal March, Mexican Hat Dance, Old MacDonald), Christmas tunes (We Three Kings, Away in a Manger, Silent Night) and Classical tunes (Ode to Joy, Moonlight Sonata, Fur Elise). There's a lot here for beginning piano students. All sheet music is in PDF format and MIDI files are also provided. (Extract From the Free Sheet Music Guide)
Free Sheet Music of all sorts
Kantorei Noten .de
Free sheet music for sacred music
Havard Digital Scores Collection
Bach, Mozart, Operas from Verdi
The Magic Flute Project
Download The Magic Flute (Die Zauberflöte) study score by W.A. Mozart in Ready-to-print PostScript or PDF file formats, or as Type 1 midi karaoke files with or without vocal tracks.
Horowitz Scores on line
All transcriptions by Horowitch
Making Music Fun 258 pieces of free sheet music for young pianists
Mfiles
Nice collection of high-quality free classical sheet music featuring music from Bach, Beethoven, Byrd, Chopin, Debussy, Mendelssohn, Rachmaninov, Saint-Saens, Satie, Tallis and many more.
Music Editions
This site contains a collection of free music, mostly Christoph Dalitz works, but there are also some pieces by old composers arranged or transcribed. A particular focus lies on choir music for three parts
Music Library 19 th century americain sheet music
The contents of 32 of these volumes (approximately 1200 pieces) have been fully scanned and are available on this site.
Musica Passion
Spanish site with lots of free Piano sheet music
Music - Scores.com
275 files PDF Non Members may download a number of these files for free.  English site
Musique Renaissance 
Page Personelle d'Alain NaigeonPDF or Encore pour Flute à bec
Musica Viva 258 pieces of free sheet music for young pianists
   
Opera Glass
Un Serveur d'informations sur l'Opéra
Pianostreet
Free inscription on the site gives right to nice scores from Bach Beethoven Cherny Debussy
Score archives .free
227 Free scores
Quatre Mains.net

website with free sheet music for piano four hands (one piano) and piano duets (two pianos).Quatre-mains.net aims to build a library of at least 100 free scores for piano four hands. We'll try to publish one new piano score per week. When we've reached number 100, new scores will still be added, but on a less regular basis. We publish easy, intermediate and difficult four hands piano music, and we'll add some studies as well.

Score on line
37 free scores for Pianos
Sheet Music USA
For both guitarists and pianists. Sorted by difficulty (beginner, advanced) Sheet music includes folk, children and classical tunes, as well as a few Christmas music selections.(GIF)
Sheet Music On line
Classical Piano Free download
Partitions gratuites pour Trompettes
Free scores for Trumpett and organ
Violin and Viola
(UK) PDF
Violin on line
Christmas Music and sacred music
Violon SheetMusic free downloads of printable violin music in PDF format scanned from public domain editions. classical music, but we also provide music for fiddle players, including Celtichymns, and more. Many of the downloads include a piano accompaniment so they can be performed with a pianist. New music is usually added several times per week, so check back regularly.
Virtualsheetmusic.com
Two dozen free downloadable demos from Bach, Chopin, Joplin, Mendelssohn and others. These are all VERY high quality scores
 
Softwares
 
SOFTWARES to view and print the music scores.
1. Acrobat Reader for PDF format
2. Postcript files Ghostscript and GS View freedowload page
3.JPEG / GIF / TIFF / PCX : you can read these files with all free images reader. To save the file, clic on the right buttom of the mouse. And then clic on "save to.." WARNING : The file can be bigger than the A4 format. You must use a software like Word, x-Press, Publisher or PowerPoint... to resize the image as a printer format.
4. Berlioz Encore Finale Igor Lime Melody assistant Mozart Noteworthy Sibelius Score
   
Directories
 
Free Sheet Music Guide
Free-Scores.com
 
Free sheet music  
France Piano
These directories  sites list free sheetmusic web site. The one I prefer is the first one on the list.
   
Music Publishers
 

Casa Ricordi
Sheetmusicplus
Di - Arezzo.com
Repertoireonline.com 
EveryNote
Musicnotes.com
G.Schirmer Inc.
Edition Wilhem Hansen (DK)
Sheetmusicdirect (digital)
Sheetmusicnow.com (digital)
Music Room (UK)
Maestronet
Musica Bona (Musique Tchèque)
Hans Sikorski (GE)
Bärenreiter
Breitkopf and Hartel (GE)
Classical Vocal Repertoire
Boosey and Hawkes
Scott Musik International
Paul Beuscher (FR)
Arioso Musique (FR)
Editions Salabert (FR)
Arpèges (Strasbourg)
Editions Alphonse Leduc
Fuzeau Classique et baroque
Editions Bourgès

 

You can also consider buying your sheetmusic.. You'll support the artists you love. I recommand Sheet Music Plus.They have over a quarter million titles to choose from. 
 

CHOPIN FREE SHEET MUSIC  
Chopin Free scores
 
IMLSP 93  
Les partitions info 26
Chopin, the Poet of the Piano Complete Chopin music and scores , fabulous site
Free scores.com 238

Mutopia

26
The Sheet Music Archives
Sheet Music USA
Nocturne.Opus 9 N°2   
Werner Icking Music Archives

La Marche funèbre de la sonate pour piano en si bemol mineur opus 35 PDF
All Chopin 's

Free Chopin Sheet Music  

 

 
Web pianopassion