Twitter has come on strong over the past year to break into the Media Power 50 top 10 for the first time. It's done this on the strength of its Promoted Tweets, Promoted Accounts and Promoted Trends ad units, plus recent moves to make 140-character ad campaigns attractive to both marketers and agencies. Last month, Twitter forged a deal with Publicis Groupe's digital agency Starcom MediaVest Group to boost Twitter ad slots for SMG clients. The deal calls for the Twitter ads' API to be integrated into SMG's analytics tool to help optimize ad buys for the agency's clients. Also in April, Twitter augmented its existing interest ad targeting with keyword targeting, allowing advertisers for the first time to target users based on the words they use in tweets or retweets. The company also bought social TV measurement company Bluefin Labs. The move signaled its official move into social TV to capture the impressions and reach analytics that go with it. “The conversation has changed from "Why Twitter?' to "How Twitter?' ” said Richard Alfonsi, VP-global online sales at Twitter. “The basics are that Twitter now has 200 million global users and growing, including b-to-b decision-makers who engage on the platform to bring them closer to what interests them.” Alfonsi said the “native ad” nature of tweets—in particular Expanded Tweets that allow marketers to display images, video and other content—is a compelling argument in favor of Twitter ads. If Twitter faces any barrier to greater adoption by advertisers, it may be one shared by social media overall: justifying the expense based on hard metrics, said Luke Bone, senior media director at technology marketing agency Mason Zimbler, Austin, Texas. “The jury is still out. We're cautious in our approach to paid social media,” Bone said. But he added that the agency will examine Twitter's new keyword targeting closely, perhaps with an upcoming pilot test. “Budget permitting, we think some of these new things from Twitter may benefit awareness,” Bone said. Twitter's pricing model has other media buyers intrigued. “The best thing that Twitter is doing is that it's really a pay-for-performance model,” said Nader Ashway, president-creative director at moddern marketing, New York. “You don't pay until you get engagement, such as follows, retweets, replies or people putting your promoted hashtags into their tweets.” Ashway said Twitter's strong suit is promoting newsworthy information, rather than gathering sales leads. “It's more of a messenger service, a way to say, "Go here to discover our brand,' ” he said.