How to determine what happens behind the scene in .Net

What tool or method can I use to see what code something like an anonymous method or LINQ statement gets compiled to? Basicly seeing what happens behind the scene?

Reflector is an excellent way to do this.

Go to View / Options / Optimization and choose "None" so that it won't try to work out what the C# originally was.

For example, the Main method of this little app:

using System;

class Test    
{
    static void Main()
    {
        string other = "hello";
        Foo (x => new { Before = other + x, After = x + other });
    }

    static void Foo<T>(Func<int, T> func) {}
}

is decompiled to:

private static void Main()
{
    <>c__DisplayClass1 class2;
    class2 = new <>c__DisplayClass1();
    class2.other = "hello";
    Foo(new Func<int, <>f__AnonymousType0<string, string>>(class2.<Main>b__0));
    return;
}

and then you look in <>c__DisplayClass1 and <>f_AnonymousType0 for more details etc.