A selection from the first listbox will populate the second list box.
I have a class created that stores the information I want to bind to.
I have stepped in and the set method of the Selected Customer is being called, and I then follow the On Property Changed("Customer Summary Details") call which goes into the "get" method of the Customer Summary Details property as expected.
I have delved into the value of the returned collection at this point, and the value within the list is the updated value, however nothing is getting reflected on the GUI, so I am puzzled as it seems the GUI is calling the get method to update it on the On Property Changed() call, but it is not reflecting visually.
Just because you use an Observable Collection does not mean that when a property in a contained item changes that the List Box or other elements will get notified.
Just when the collection changes (add/remove items) will the listbox be notified. If your IItem implementation is being provided by your database then you have to use whatever mechanism your database code provides to allow you to inject property notification into the objects it creates (I personally use Castle Dynamic Proxy to do this with NHibernate).
Similar to @Blam, I suspect that the Has Information implementation in the IItem interface does not implement INotify Property Changed.To do this, I have created a separate property on the View Model called Customer Summary Details which contains simply a get, that returns the collection contained within the customer I mentioned above.In the XAML I have bound the Items Source to the Customer Summary Details Property.xaml in Main Page: and removing the unused property might get you closer to where you want to be.As an aside, you don't see this pattern used very often because inheriting from a collection class isn't generally considered very useful unless you're adding new functionality.I'm using the MVVM pattern and want to update a List View using an observable collection. Namespace: @Halo Mediaz Not quite - Observable COllection implements INotify Collection Changed so that when items are added/removed then anything bound gets updated.I went through several SO questions, but cannot see what I'm doing wrong. You still need to implement INotify Property Changed and have individual properties notify that they've updated otherwise the binding subsystem will never know that the observable collection was assigned to the property.In order to achieve your goal one of options is to change the IItem from interface to a class which implements INotify Property Changed interface (or implement it in the IItem concrete type), and hook it with the View Model's Property Changed delegate (remember to unsubscribe it). There is a background task which receives external updates to the content of the list.The alternative is to create a wrapper for each of your data models in the viewmodel and add that functionality yourself.Observable Collection only notifies the collection changes not the changes in each of the item.