You’ve read all of your free items this month. To register, get added benefits and unlimited access to articles, Become a Member. Already a Member? Sign in. Advertising Age Article Abstract How Agencies Can Fend Off the Threat of Marketing Services Moving In-House Help Clients Justify the Costs of Working With Your Shop By Articulating Value And Being Collaborative By Adam Kleinberg, Published on September 13, 2013 21 Want more Access, Content & Connections? Upgrade to Membership. We are glad you are enjoying Advertising Age. To get uninterrupted access and additional benefits, become a member today. Become a Member Already a member? Log in.