Introduction to Arithmetic Groups
by Dave Witte Morris

Here are the chapters in the current version:

1. What is a Locally Symmetric Space?
2. Geometric Meaning of R-rank and Q-rank
3. Introduction to Semisimple Lie Groups
4. Basic Properties of Lattices
5. What is an Arithmetic Lattice?
6. Examples of Lattices
7. SL(n,Z) is a lattice in SL(n,R)
   
8. Real Rank
9. Q-rank
10. Ergodic Theory
11. Amenable Groups
12. Kazhdan's Property (T)
13. Margulis Superrigidity Theorem
14. Normal Subgroups of Gamma
15. Arithmetic Lattices in Classical Groups
16. Construction of a Coarse Fundamental Domain
17. Ratner's Theorems on Unipotent Flows
    

• Appendices:
  
• Assumed Background
• Which Classical Groups are Isogenous?
• Central Division Algebras over Number Fields
• A Quick Look at S-Arithmetic Groups