I have a user control (ascx) called _CountryList.
This control binds to a dataSet read from XML that came from a webService (with caching) that provides a list of countries.

This user control is then used on every web form that needs a listbox of countries (eg: Customer Registration, etc.)

So far this is all working great....

QUESTION: How do I access the selected country from within the code behind a web form that has the user control embedded?

CODE SNIPPET: (why does this not work?)
================================================== ===
Public Class Register
  Protected WithEvents Countries As System.Web.UI.UserControl

  Private Sub RegisterBtn_Click(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles RegisterBtn.Click
    If Page.IsValid Then
      'Get the Country
      Dim lbCountry As ListBox = DirectCast(Countries.FindControl("lbCountry"), ListBox)
      Dim Country As String = lbCountry.SelectedItem.Value
      lbCountry = Nothing
  End Sub
End Class
================================================== ===
By my reckoning Country should contain the selected value.
Instead I get: 'Object reference not set to an instance of an object'

Thoughts, anyone ???

In your ascx code behind file you have to declare all form fields you plan to use in the container Web d\forms as public properties:
Public Property MyListBoxvalue
Get
return ListBox1.SelectedItem.Value
End Get
...
and than u can use MyListBoxvalue variable in .aspx page containing user control.
HTH.

...but the Soon is eclipsed by the Moon

ok, so I have a public property in the ascx.

What would the syntax be in the code behind the form for accessing it?

I'm not sure why you are creating a new listbox when you have the user control?
Does the dataset fill a web control dropdownlist in the ascx user control?
If you have a public property that will display the country that is selected in the user control listbox, you should then be able to access it as follows:

Private Sub RegisterBtn_Click(ByVal sender As Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles RegisterBtn.Click
Dim Country As String

If Page.IsValid Then
      'Get the Country
      Country = Countries.Country
End Sub

In the ascx you should have an event, lbCountries_SelectedIndexChanged that fires when the user selects a country, which then assigns that selecteditem to the property.