SelectMany() Cannot Infer Type Argument — Why Not?

The type returned by the delegate you pass to SelectMany must be an IEnumerable<TResult>, but evidently, Office doesn’t implement that interface. It looks like you’ve simply confused SelectMany for the simple Select method.

• SelectMany is for flattening multiple sets into a new set.
• Select is for one-to-one mapping each element in a source set to a new set.

I think this is what you want:

foreach (var office in CurrentEmployee.EmployeeOffices.Select(eo => eo.Office))