How to access to control references in WPF Xaml?

For accessing any element in code behind you will need to set x:Name directive. It tells the XAML parser to add a field representing the named element to the automatically generated portion of the Window class just like Winforms.

In a WPF application, there’s no requirement to name each and every element. You should name only those elements which you want to programatically interact with.

An example:

<TextBlock x:Name="tblText" Text="Stackoverflow rocks."></TextBlock>

EDIT:
I used the following code and I was able to access the list view:

namespace WpfApplicationUnleashed
{
    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {    
        public Window1()
        {
            InitializeComponent();
            EffectsListView.Width = 10;
        }    
    }
}

<Window x:Class="WpfApplicationUnleashed.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:sys="clr-namespace:System;assembly=mscorlib"
        xmlns:local="clr-namespace:WpfApplicationUnleashed"
        Title="Window1" >
    <DockPanel>
        <ListView x:Name="EffectsListView"></ListView>
    </DockPanel>
</Window>

have you set their x:Name="ControlName" property in xaml?

Here is more information on x:Name directive.

For example:

<Button x:Name="Button1">Click Me</Button>