 <p>In your edit you specify that your helper class is in a seperate assembly. If you want to avoid references and you have control over your app.config files you could put an </p> <pre><code>&lt;add key="typeOfSystem" value="Forms|Web"/&gt; </code></pre> <p>in your projects and access it with</p> <pre><code>ConfigurationManager.AppSettings["typeOfSystem"] </code></pre> <p>using <a href="http://msdn.microsoft.com/en-us/library/system.configuration.configurationmanager.aspx" rel="nofollow noreferrer">ConfigurationManager</a> along with its property <a href="http://msdn.microsoft.com/en-us/library/system.configuration.configurationmanager.appsettings.aspx" rel="nofollow noreferrer">AppSettings</a>. Don't forget to add a reference to <code>System.Configuration</code> in your project. Note that you get the AppSettings of the hosting application. By doing this you <em>need</em> to add a key in your parent application's app.config, or output some error or warning if it's not specified perhaps.</p>