Spartan studies have recently gone through a major paradigm shift, and scholars no longer believe much of what used to be considered common knowledge about Sparta, so it's important to get recent works that are most up-to-date on the scholarship. The most accessible new textbook is Nigel Kennell's Spartans: A New History (2010), but the most comprehensive by far is the brand new Companion to Sparta (ed. A. Powell, 2017).

Kennell's own work is mostly on the Spartan upbringing, and his The Gymnasium of Virtue: Education and Culture in Ancient Sparta (1995) offers a masterclass in poking through the Spartan mirage. More recent is Jean Ducat's Spartan Education (2006). There is also the (dryer, but mind-blowing for those with the stamina) work of Stephen Hodkinson on Spartan economy, society, and supposed austerity - see his Property and Wealth in Classical Sparta (2000). Apart from Ducat's work on helots (which is in French), much of the new work on Sparta is done through the edited volumes that result from the biannual International Sparta Seminar in Nottingham (UK); see especially Spartan Society (ed. T. Figueira, 2004) and Sparta: New Perspectives (ed. S. Hodkinson/A. Powell, 2009).

I hope this helps!

If you're interested in a slightly different take on it then I can highly recommend Sarah Pomeroy's book "Spartan Women".

Check out our booklist! It has some Sparta in there.