Static fields in a base class and derived classes

static members are entirely specific to the declaring class; subclasses do not get separate copies. The only exception here is generics; if an open generic type declares static fields, the field is specific to that exact combination of type arguments that make up the closed generic type; i.e. Foo<int> would have separate static fields to Foo<string>, assuming the fields are defined on Foo<T>.

As pointed out in other answer, the base class static field will be shared between all the subclasses. If you need a separate copy for each final subclass, you can use a static dictionary with a subclass name as a key:

class Base
{
    private static Dictionary<string, int> myStaticFieldDict = new Dictionary<string, int>();

    public int MyStaticField
    {
        get
        {
            return myStaticFieldDict.ContainsKey(this.GetType().Name)
                   ? myStaticFieldDict[this.GetType().Name]
                   : default(int);
        }

        set
        {
            myStaticFieldDict[this.GetType().Name] = value;
        }
    }

    void MyMethod()
    {
        MyStaticField = 42;
    }
}