If I cared what the order was, I&#x27;d expect that I&#x27;d have to order it myself, e.g.:<p><pre><code>  var foo = things.SelectMany(thing=&gt;thing.SubThings).OrderBy(subthing=&gt;subthing.PropertyICareAbout)
</code></pre>
Particularly if things is some interface that I don&#x27;t know the details of, like IEnumerable, ICollection or IDictionary.