I recently watched a TED-Ed video about Spartan society in Ancient Greece. The video discusses how Spartans were forbidden to keep records. Then it goes on to describe how the Spartans learned to read and write. Why would they need to know these skills if they could never use them?
Aside from works by academics, much of what has been written about Sparta has been exaggerated or sensationalized and, even in ancient times, the Spartans themselves did not discourage many of these 'myths'. There are many documented examples of Spartans using writing, including the recording of laws and oracles, and the literacy rate amongst women may well have been higher than in any other ancient Greek city state.
In his book Spartan Law, Prof. D. M. MacDowell argues convincingly that one should not interpret the claim that Spartans did not write down their laws too strictly, especially when it comes to amendments to the original constitution. Plutarch quotes from a text of one of the laws. On this, MacDowell says:
...it seems clear...that it is a geuine early Spartan document. Nearly all modern scholars accept it as such,...
...he [Plutarch] goes on to quote a poem of Tyrtaios which refers to the law with the rider. Thus it appears that at least one of 'the laws of Lykourgos' was written by the time of Tyrtaios, before the end of the seventh century.
Further evidence concerns the procedure for legislation proposed by King Agis IV (died 241 BC), 'who claimed to be a champion of tradition' (MacDowell):
From this evidence it appears that the procedure had three stages. First, the proposal was put in writing and brought forward by one or more of the ephors.
There are a number of references in Herodotus to the Spartans not only being literate but also keeping records. For example, they kept records of oracles from Delphi.
We also know that the Spartans used writing when sending messages. The first, a fine example of Spartan brevity (and helplessness when left without a leader), is a message which was intercepted by the Athenians after they had defeated the Spartan navy at the Battle of Cyzicus in 410 BC. The Spartan admiral, Mindaros, was killed during the battle. Xenophon records this in 'Hellenika' thus:
A letter that had been sent to Lacedaemon by Hippokrates, Mindaros' vice-admiral, was capyured and brought to Athens. It said, "Ships gone, Mindaros dead, men starving;don't know what to do."
In this second example, Paul Cartledge, in his book 'The Spartans', drawing on Herodotus, writes of a message sent by the exiled former King Demaratus which puzzled all but Gorgo, wife of King Leonidas I:
A messenger arrived in Sparta bearing an apparently blank wax tablet (two leaves of wood, covered with wax and folded together). 'No one,' Herodotus relates, 'was able to guess the secret' - no one except Gorgo, that is. She calmly told the authorities that if the wax were scraped off, they would find the message written in ink on the wood beneath, and so indeed it proved.
Interestingly, Spartan women were given a formal education and could at the very least read, unlike their counterparts in other Greek city states (including Athens) who received no formal education (though some girls from wealthy families were taught to read and write). Evidence of this can be found in Spartan sayings recorded by Plutarch:
When some woman heard that her son had been saved and had escaped from the enemy, she wrote to him: 'You've been tainted by a bad reputation. Either wipe this out now or cease to exist.'
A final note - when dealing with Sparta, beware the Spartan myth. Some of what one finds outside of modern academic work on Sparta can be very misleading. As Cartledge notes,
The Spartan myth was persuasively labelled a 'mirage' in the 1930s, by the French scholar Francois Ollier, because the relation between the myth and reality was and is sometimes so hard to perceive without distortion.
Sources: D.M.MacDowell, 'Spartan Law'; Paul Cartledge, 'The Spartans'; Anne Pearson & The British Museum, 'Ancient Greece'; R. J. A. Talbert, 'Plutarch on Sparta'; The Landmark Xenophon's Hellenika (trans: John Marincola)