Declare a const array

Yes, but you need to declare it readonly instead of const:

public static readonly string[] Titles = { "German", "Spanish", "Corrects", "Wrongs" };

The reason is that const can only be applied to a field whose value is known at compile-time. The array initializer you've shown is not a constant expression in C#, so it produces a compiler error.

Declaring it readonly solves that problem because the value is not initialized until run-time (although it's guaranteed to have initialized before the first time that the array is used).

Depending on what it is that you ultimately want to achieve, you might also consider declaring an enum:

public enum Titles { German, Spanish, Corrects, Wrongs };

This is the only correct answer. You cannot currently do this.

All the other answers are suggesting using static read-only variables which are similar to, but not the same as a constant. A constant is hard coded into the assembly. A static read only variable is settable once, probably as an object is is initialized.

These are sometimes interchangeable, but not always.

EDIT: I thought I'd throw this in, as it seems like the person who asked the question was a little fuzzy about arrays. When you declare an array, it is a pointer to a segment of memory that contains the array. It is very simple in that it is just an address, with no complex logic controlling if it is readable or writable. It gives you a pointer, and you can do whatever you want with it.

This is part of the reason why it is a little tricky to make an immutable array. You could write a class that wraps the array and only allows reading of it by returning a copy, but then it really isn't just an array anymore, it is an object that wraps an array.

Some people have suggested using static, or readonly to simulate the behavior you would see if you could create const array. These have some side effects that might not be obvious to the casual reader.

To truly get a const array, there would need to be an update to C# and the MSIL underlying code to allow reading from an array, but no writing. The other proposals on this page are various creative ways to work around this problem.

You can't create a 'const' array because arrays are objects and can only be created at runtime and const entities are resolved at compile time.

What you can do instead is to declare your array as "readonly". This has the same effect as const except the value can be set at runtime. It can only be set once and it is thereafter a readonly (i.e. const) value.

You can declare array as readonly, but keep in mind that you can change element of readonly array.

public readonly string[] Titles = { "German", "Spanish", "Corrects", "Wrongs" };
...
Titles[0] = "bla";

Consider using enum, as Cody suggested, or IList.

public readonly IList<string> ITitles = new List<string> {"German", "Spanish", "Corrects", "Wrongs" }.AsReadOnly();