ArcSight Names Joni Kahn Senior Vice President of Services and Support

Former EVP of BearingPoint to Lead Professional Services, Technical Support and Customer Success Organization

CUPERTINO, CA – July 29, 2009 – ArcSight, Inc. (NASDAQ: ARST), a leading global provider of security and compliance management solutions that protect enterprises and government agencies, today announced the appointment of Joni Kahn as senior vice president of services and support. With more than 20 years experience in the technology and consulting industries, Kahn adds a breadth of experience and a focus on customer success to the senior management team.

As SVP of services and support, Kahn will be responsible for overseeing the ArcSight global professional services, technical support organizations and customer success organization.

Kahn was formerly executive vice president at BearingPoint where she managed a team of over 3,000 professionals and was responsible for North American delivery of enterprise applications, systems integration and managed services solutions. She also oversaw global development centers in India, China and the U.S. Prior to BearingPoint, Kahn was senior group vice president for worldwide professional services for Business Objects, a business intelligence software maker based in San Jose, where she led the applications and services division that supported that company's transformation from a products company to an enterprise solutions company. She was also a member of the KPMG Consulting Executive Committee, where she helped grow the firm’s consulting business from $700 million to $2.5 billion.

"Joni is a true industry veteran with more than a decade of experience managing large services teams," said Tom Reilly, president and CEO of ArcSight. "Our customers count on ArcSight to protect their businesses against the increased level of sophisticated cyber-threats. Joni’s experience and unique ability to deliver solution-oriented best practices through an expanding community of skilled professionals will help fulfill our number one business imperative of focusing on customer success. Our partner community and customer base will benefit greatly from her leadership at ArcSight which in turn will continue to fuel our business growth."

About ArcSight

ArcSight (NASDAQ: ARST) is a leading global provider of security and compliance management solutions that protect businesses and government agencies. ArcSight identifies, assesses, and mitigates both internal and external cyber threats and risks across the organization for activities associated with critical assets and processes. With the market-leading ArcSight SIEM platform, organizations can proactively safeguard their assets, comply with corporate and regulatory policy and control the risks associated with cyber-theft, cyber-fraud, cyber-warfare and cyber-espionage. For more information, visit www.arcsight.com.

Cautionary Statement Regarding Forward Looking Statements

This news release contains forward-looking statements, including without limitation those regarding anticipated benefits of ArcSight and its partner community and customer base from Ms. Kahn’s leadership at ArcSight. These forward-looking statements are subject to material risks and uncertainties that may cause actual results to differ substantially from expectations. Investors should consider important risk factors, which include: the risk that Ms. Kahn may be unable to make the contributions that are anticipated; and other risks detailed under the caption “Risk Factors” in the ArcSight Annual Report on Form 10 K filed with the Securities and Exchange Commission, or the SEC, on July 9, 2009 and the company’s other filings with the SEC. You can obtain copies of the company’s Annual Report on Form 10 K and its other SEC filings on the SEC’s website at www.sec.gov.