The Web design industry is undergoing a period of rapid change — and over the next 12 to 18 months, a new kind of agency will emerge from today's fragmented array of Web design providers. These firms will draw on the user-centered design and technology prowess of today's interactive agencies, the strategic advising capabilities of traditional ad agencies, and the change management expertise of management consultants — all while honing their ability to deliver Web sites that effectively integrate with other channels. Web site owners looking to hire an agency now need to consider how candidate firms will evolve over the next few years by probing into these five areas.