And of course , how conveniently omitted is Byzantium, which is said to have had a literacy rate (meaning both reading and writing) of upwards of 40%. All too often people forget that the Roman Empire existed in the European Middle Ages.

During the height of the medieval Byzantine Empire (say for example AD 900-1180) primary, secondary, and tertiary education were available to most citizens, and this is highlighted by the fact that the Byzantine emperors distributed lengthy military manuals which were expected to be read by generals and their officers, there were authors who wrote novels for the masses, scholars wrote of education in poems and other literature, and there is even visual evidence in works such as the Madrid Skylitzes of children attending school.

A brief overview of literacy/education in Byzantine society:

Generally educated: The Emperor and the Imperial family, Imperial administrators, Aristocrats, Clergy, Generals, Military Officers, and Tagmata soldiers, Intelligentsia, Merchants, Burghers, Artisans

Generally uneducated: Farmers, Slaves, Rowers, Fishermen, Beggars, Hunters, Thieves, Performers

The biggest problem faced by historians is discerning between modern concepts of 'literacy' and medieval 'litteratus'. Michael Clanchy pithily puts it: 'To ask, 'Were laymen illiterate?' is a tautology: of course laici were illiterati because these terms were synonymous'. (Clanchy, 2013, 233).

This statement revolves around a conception of who was litteratus and who was not. This was a concept propagated in the medieval period and by the clergy (unsurprisingly).

litteratus : illiteratus

clericus : laicus

These are two axioms which were repeated (and partially true) throughout the early to high middle ages. The first was of Roman origin and fairly obvious. The second was a medieval creation (Gr. kleros, 'selection by lot' -> 'elect' of God : Gr. laos, 'people; crowd'). Between 500-1000, the reduction in the number of learned men coincided with the expansion of Christianity through the conversion of the barbarians. Clerici became associated with litterati despite the two concepts originally possessing nothing in common. When standards declined litterati became associated with merely being literate.

Compared to the literrati of Rome or of the twelfth-century this was a far poorer meaning than 'learned' or 'lettered', yet they solidified a position of authority by engendering a hostility towards those without even the mean skills they possessed.

The realities of the world they faced made them unsure of their position, they lauded the exceptional (for they were exceptional) rulers, such as Charlemagne and Alfred, who encouraged their nobility to become better Latinists.

By the time we reach the twelfth-century the constant repetition of these axioms:

litteratus : illiteratus clericus : laicus

Had made them synonymous.

A usage of speech has taken hold whereby when we see someone litteratus, immediately we call him clericus. Because he acts the part that is a cleric's, we assign him the name ex officio. Thus if anyone is comparing a knight who is litteratus with a priest who is ignorant, he will exclaim with confidence and affirm with an oath that the knight is a better clericus than the priest ... This improper usage has become so prevalent that whoever gives attention to letters, which is clerkly, is named clericus.

This quote comes from Philip of Harvengt in the 1170s (cited from Clanchy, 2013, 229) and demonstrates the manner in which writers 'deplored' that knights and clergy no longer fit into their 'traditional roles'. Matthew Paris would describe one of Henry III's stewards as 'miles litteratus sive clericus militaris, 'a literate knight or knightly clerk'' (Clanchy, 2013, 230).

So what can we say about medieval literacy in the modern sense?

Clanchy argues that reading and writing were not automatically coupled - the technical skill of wielding a quill or using (expensive!) parchment made it difficult, as the practice of reading aloud made it often unnecessary to read oneself. Scribes and notaries would be employed to draft legal documents, although there were exceptions to these rules (Simon de Montfort's son drafted his father's will in a beautiful hand).

In Clanchy's widely accepted thesis it was the emergence of bureaucratic documentation (the proliferation of documents) which forced the laity to harness the skills of the litterati, meagre though they might seem today. Practical, pragmatic literacy flourished and the development of vernacular literary traditions would soon keep pace with the Latin language of the courts, chancery, and church.

For what is quite literally the book on the subject:

M.T. Clanchy, From Memory to Written Record: England 1066-1307, 3rd Ed., 2013.

You use literary in the title, but talk about literacy in the body. As /u/TheGreenReaper7 noted, writing and reading don't necessary go hand in hand. Furthermore, I'd argue that being able to write doesn't necessarily make you literary. It makes you literate. If you can write but are a copyist, are you literary? What if you only use it for writing grocery lists?

So there is a group that was non-clergy but literate in medieval society. If you haven't already guessed by my flair, it was Jews!

While no one bothered keeping literacy stats on medieval Jews, contemporary writers seem to assume literacy among the religious population. There's a commandment in the Talmud (Babylonian Talmud, Brakhot 8a) that requires regular reading of the bible in Hebrew and in Aramaic. That doesn't indicate literacy, because there are other texts which indicate widespread illiteracy, and it's not all that explicit about reading on your own anyway.

However, later writers in discussing it are more explicit about it being private individual reading. Maimonides wrote:

אע''פ שאדם שומע כל התורה כולה בכל שבת בצבור חייב לקרות לעצמו בכל שבוע ושבוע סדר של אותה שבת שנים מקרא ואחד תרגום.

And even though a person hears the entirety of the Torah every Sabbath publically, they are obligated to read the portion for that Sabbath themselves each and every week; the bible twice, the [Aramaic] translation once. (Mishneh Torah, Sefer Ahava, Hilchot Tefillah, 13:25).

He's from the 12th century, and assumes that Jews can read Hebrew and Aramaic. A bit later, R' Yosef Karo uses similar language:

אף על פי שאדם שומע כל התורה כולה כל שבת בצבור חייב לקרות לעצמו בכל שבוע פרשת אותו השבוע שנים מקרא ואחד תרגום אפילו עטרות ודיבן: אם למד הפרשה בפירוש רש''י חשוב כמו תרגום וירא שמים יקרא תרגום וגם פירוש רש''י:

And even though a person hears the entirety of the Torah every Sabbath publically, they are obligated to read the portion for that week every week; the bible twice, the [Aramaic] translation once, even "'atarot ve-divon" [a bit with no Aramaic translation]. And if he learned with the commentary of Rashi, it counts as the translation, though a heaven-fearing person reads with both the [Aramaic] translation and the commentary of Rashi (Shulchan Arukh, Orach Chayim, chapter 285).

There's also Kuzari, a 12th century text. It explains the (still extant) practice of Jews swaying while praying by saying that Jews would lean over a communal prayerbook placed on the floor. You'd be standing up praying, lean over to read the next bit, stand back up, etc. Particularly interestingly, it mentions people bringing books from home, indicating that private ownership and use of written books existed:

ומא אט'נה אלא מן אלבאב אלד'י נחן פיה, למא אמכן גמלה מנהם אלקראה פה אחד אמכן אן יגתמע עשרה ואכת'ר עלי מצחף ואחד. ולד'לך צארת מצאחפנא כבארא פילגא כל ואחד מן אלעשרה אלי אלמיל מע אלאחיאן לרויה' אלחרף, ת'ם יעוד. ויכון הד'א מילא ורגועא לכון אלמצחף פי אלארץ'. ויכון הד'א אלסבב אלאול, ת'ם צארת עאדה מן אלרויה ואלמשאהדה ואלמחאכאה אלתי הי פי טבע אלנאס. וג'ירנא יקרא כל ואחד פי מצחפה ויצ'ם מצחפה אלי עינה או ינצ'ם הו אליה בקדר מא יריד מן ג'יר אן יצ'איקה צאחבה פיה, פליס יחתאג אלי מיל וארתפאע.

וְאֵינֶנִּי סָבוּר שֶׁהוּא אֶלָּא מִצַּד הָעִנְיָן שֶׁאֲנַחְנוּ בוֹ, כִּי מִפְּנֵי שֶׁיְּכוֹלִים לִקְרֹא רַבִּים מֵהֶם פֶּה אֶחָד הָיָה אֶפְשָׁר שֶׁיִּתְקַבְּצוּ עֲשָׂרָה מֵהֶם אוֹ יוֹתֵר עַל סֵפֶר אֶחָד, וּבַעֲבוּר זֶה הָיוּ סְפָרֵינוּ גְדוֹלִים, וְיִצְטָרֵךְ כָּל אֶחָד מֵהָעֲשָׂרָה שֶׁיִּטֶּה עִם הָעִתִּים לְעַיֵּן הַתֵּבָה, וְיָשׁוּב, וְהוּא נוֹטֶה וְשָׁב תָּמִיד מִפְּנֵי שֶׁהַסֵּפֶר בָּאָרֶץ, וְהָיָה זֶה הַסִּבָּה הָרִאשׁוֹנָה, וְאַחַר כֵּן שָׁב מִנְהָג מִפְּנֵי הַהִסְתַּכְּלוּת וְהָרְאִיָּה וּלְהִדַּמּוֹת כַּאֲשֶׁר הוּא טֶבַע מִבְּנֵי אָדָם. וְזוּלָתֵנוּ קוֹרֵא כָּל אֶחָד בְּסִפְרוֹ וּמְקָרְבוֹ אֶל עֵינָיו אוֹ יִקְרַב הוּא אֵלָיו כְּפִי רְצוֹנוֹ, מִבְּלִי שֶׁיָּצַר עָלָיו חֲבֵרוֹ, וְאֵינֶנּוּ צָרִיךְ שֶׁיִּטֶּה וְיָשׁוּב

My personal belief is that it stands in connexion with the subject under discussion. As it often happened that many persons read at the same time, it was possible that ten or more read from one volume. This is the reason why our books are so large. Each of them was obliged to bend down in his turn in order to read a passage, and to turn back again. This resulted in a continual bending and sitting up, the book lying on the ground. This was one reason. Then it became a habit through constant seeing, observing and imitating, which is in man's nature. Other people read each out of his own book, either bringing it near to his eyes, or, if he pleased, bending down to it without inconveniencing his neighbour. There was, therefore, no necessity of bending and sitting up.

That's the original Judeo-Arabic, the Hebrew translation of ibn Tibbon, and the English translation of Hartwig Hirschfeld.

There also is a custom which involves having small children know letters, though I'm having trouble finding a non-recent text attesting to the practice (and by extension childhood literacy)--it may be a rather recent innovation.

That's gone on much longer than it probably needed to. Point is, the religious public among Jews in the Middle Ages could probably read.

Check out Frederick II of the Holy Roman Empire (1212-1220). He spoke six languages: Latin, Sicilian, German, French, Greek and Arabic. His poetic patronage and contributions were influential on Dante and the rise of poetry in modern Italian. He was a religious skeptic and excommunicated by Pope Gregory IX. Though, he did retain many ties with orthodox Christianity. He was read in Aristotle and keenly interested in natural science, producing De Arte Venandi cum Avibus ("The Art of Hunting with Birds"). He was also interested in physiology, astronomy, and law.

For further reading see:

Frederick II: The Wonder of the World, by Richard Bessler

Late Medieval Italy holds many prime examples of a literate society, enabled by the independence of the commune republics of the 14th and 15th centuries. In the majority of towns and cities across Northern Italy there were state-funded/assisted education systems for teaching elementary literacy.

This was to cater for the explosion in Italian vernacular literature that was appearing in the form of sermons, business and family correspondence, account books and civic memoirs. It became practical for states to fund the education of its inhabitants and most towns employed tutors to teach children their ABCs and basic grammar. From the 1300s, communes started giving incentives for teachers to come to their city, besides paying their salaries, such as exemption from military service (Genoa and Ferrara), free citizenship (Palermo), free housing (Verona) etc.

The Florentine Giovanni Villaini remarked at the end of the 1330s that "8000 to 10 000 boys and girls were learning to read" - which works out to about 70 to 80% of Florentine children in school in the mid-14th century. The necessity to educate children so that they could take part in business and social interaction demonstrates that there was a large non-clergy literate social group in urban Italian society, and it wasn't just the rich.

Source - John M. Najemy, Italy In the Age of the Renaissance: 1300-1500