ExpandableListView Mono for Android
using System;
using Android.App;
using Android.Content;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;
using System.Collections.Generic;
namespace MonoAndroidApplication2
{
    [Activity(Label = "Expandable List Activity", MainLauncher = true )]
    public class Activity1 : ExpandableListActivity
    {
        IExpandableListAdapter mAdapter;
        String NAME = "NAME";
        String IS_EVEN = "IS_EVEN";
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);
            List< IDictionary <String , object >> groupData = new List< IDictionary < string , object >>();
            List< IList<IDictionary< String, object>>> childData = new List < IList < IDictionary < string, object>>>();
            for ( int i = 0; i < 20; i++)
            {
                Dictionary< String, object > curGroupMap = new Dictionary < string , object >();
                groupData.Add(curGroupMap);
                curGroupMap.Add(NAME, "Group " + i);
                curGroupMap.Add(IS_EVEN, (i % 2 == 0) ? "This group is even" : "This group is odd");
                List< IDictionary <String , object >> children = new List< IDictionary < string , object >>();
                for ( int j = 0; j < 15; j++)
                {
                    Dictionary< String, object > curChildMap = new Dictionary < string , object >();
                    children.Add(curChildMap);
                    curChildMap.Add(NAME, "Child " + j);
                    curChildMap.Add(IS_EVEN, (j % 2 == 0) ? "This child is even" : "This child is odd");
                }
                childData.Add(children);
            }
            // Set up our adapter
            mAdapter = new SimpleExpandableListAdapter (
                    this,
                    groupData,
                    Android.Resource.Layout.SimpleExpandableListItem1,
                    new String[] { NAME, IS_EVEN },
                    new int[] { Android.Resource.Id.Text1, Android.Resource.Id.Text2 },
                    childData,
                    Android. Resource. Layout.SimpleExpandableListItem2,
                    new String[] { NAME, IS_EVEN },
                    new int[] { Android.Resource .Id.Text1, Android.Resource.Id.Text2 }
                    );
            SetListAdapter(mAdapter);
        }
    }
}