using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var smartGroups = GetGroups() as IEnumerable<SmartGroup>;

        Console.WriteLine("Is the cast from a IList<BaseClass> to an IEnumerable<SuperClass> valid: {0}", smartGroups != null);

    }

    public static IList<Group> GetGroups() {

        var groups = new List<Group>();

        for(var i = 0; i < 5; i++) {

            groups.Add(new SmartGroup());   

        }

        return groups;

    }

}

​

public class Group {

}

​

public class SmartGroup : Group {

}