Header.cs

using Android.Views;
using Android.Widget;

namespace ListViewWithHeaders.Items
{
    public class Header : IItem
    {
        public string HeaderName { get; set; }

        public View GetView(LayoutInflater inflater, View convertView)
        {
            var view = convertView ?? inflater.Inflate(Resource.Layout.Header, null);

            var text = view.FindViewById<TextView>(Resource.Id.separator);
            text.Text = HeaderName;

            return view;
        }
    }
}

Header.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

  <TextView
      style="?android:attr/listSeparatorTextViewStyle"
      android:id="@+id/separator"
      android:text="Header"
      android:layout_width="fill_parent"
      android:layout_height="wrap_content"
      android:background="#757678"
      android:textColor="#f5c227" />

</LinearLayout>

IItem.cs

using Android.Views;

namespace ListViewWithHeaders.Items
{
    public interface IItem
    {
        View GetView(LayoutInflater inflater, View convertView);
    }
}

Item.cs

using Android.Views;
using Android.Widget;

namespace ListViewWithHeaders.Items
{
    public class Item : IItem
    {
        public string ItemName { get; set; }
        public string SubName { get; set; }

        public View GetView(LayoutInflater inflater, View convertView)
        {
            var view = convertView ?? inflater.Inflate(Resource.Layout.Item, null);

            var itemText = view.FindViewById<TextView>(Resource.Id.list_content1);
            var itemSubText = view.FindViewById<TextView>(Resource.Id.list_content2);

            itemText.Text = ItemName;
            itemSubText.Text = SubName;

            return view;
        }
    }
}

Item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal" >

  <TextView
      android:id="@+id/list_content1"
      android:layout_width="wrap_content"
      android:layout_height="match_parent"
      android:layout_margin="5dip"
      android:clickable="false"
      android:gravity="center"
      android:longClickable="false"
      android:paddingBottom="1dip"
      android:paddingTop="1dip"
      android:text="sample"
      android:textColor="#ff7f1d"
      android:textSize="17dip"
      android:textStyle="bold" />

  <TextView
      android:id="@+id/list_content2"
      android:layout_width="wrap_content"
      android:layout_height="match_parent"
      android:layout_margin="5dip"
      android:clickable="false"
      android:gravity="center"
      android:linksClickable="false"
      android:longClickable="false"
      android:paddingBottom="1dip"
      android:paddingTop="1dip"
      android:text="sample"
      android:textColor="#6d6d6d"
      android:textSize="17dip" />

</LinearLayout>

ItemsWithHeaderListAdapter.cs

using System.Collections.Generic;
using Android.Content;
using Android.Views;
using Android.Widget;
using ListViewWithHeaders.Items;

namespace ListViewWithHeaders.Adapters
{
    public class ItemsWithHeaderListAdapter : BaseAdapter<IItem>
    {
        private readonly LayoutInflater _inflater;
        public List<IItem> Items { get; private set; }

        public ItemsWithHeaderListAdapter(Context context)
        {
            _inflater = LayoutInflater.FromContext(context);
            Items = new List<IItem>();
        }

        public override long GetItemId(int position) { return position; }

        public override View GetView(int position, View convertView, ViewGroup parent)
        {
            return Items[position].GetView(_inflater, convertView);
        }

        public override int Count { get { return Items.Count; } }

        public override IItem this[int position] { get { return Items[position]; } }
    }
}

Main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
  <ListView
    android:id="@+id/listView"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    />
</LinearLayout>

MyListActivity.cs

using Android.App;
using Android.Widget;
using Android.OS;
using ListViewWithHeaders.Adapters;
using ListViewWithHeaders.Items;

namespace ListViewWithHeaders
{
    [Activity(Label = "ListViewWithHeaders", MainLauncher = true, Icon = "@drawable/icon")]
    public class Activity1 : Activity
    {
        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.Main);

            var listView = FindViewById<ListView>(Resource.Id.listView);
            var adapter = new ItemsWithHeaderListAdapter(this);
            listView.Adapter = adapter;

            adapter.Items.Add(new Header { HeaderName = "Header 1"});
            adapter.Items.Add(new Item { ItemName = "Text 1", SubName = "Rabble rabble" });
            adapter.Items.Add(new Item { ItemName = "Text 2", SubName = "Rabble rabble" });
            adapter.Items.Add(new Item { ItemName = "Text 3", SubName = "Rabble rabble" });
            adapter.Items.Add(new Item { ItemName = "Text 4", SubName = "Rabble rabble" });
            adapter.Items.Add(new Header { HeaderName = "Header 2" });
            adapter.Items.Add(new Item { ItemName = "Text 5", SubName = "Rabble rabble" });
            adapter.Items.Add(new Item { ItemName = "Text 6", SubName = "Rabble rabble" });
            adapter.Items.Add(new Item { ItemName = "Text 7", SubName = "Rabble rabble" });
            adapter.Items.Add(new Item { ItemName = "Text 8", SubName = "Rabble rabble" });

            listView.PostInvalidate();
        }
    }
}