– Office Hours: 8:30 am to 4:30 pm – Monday through Friday – Closed ALL Federal Holidays

About Us

Cornerstone Specialty Insurance Service, Inc. (CSIS) is an independent full service brokerage firm. We provide insurance placement for business clients of various industries. In the dynamic marketplace of the insurance industry, we always strive to provide our clients with superior professional service designed to control the cost of insurance and reduce the risk of loss. Our commitment to our clients continues through the policy year as they are encouraged to consult us on matters of risk management, quality assurance, continuing education and all other liability matters.

As an independent insurance broker with allegiance to no specific insurance carrier, we take seriously our responsibility to represent you and your business to the insurance marketplace to find the best program, both in pricing and protection.

CSIS has earned a reputation among its clients and insurers for attention to detail with timely and professional services. Our business is founded on principals that seem to be missing in this day and age: integrity; honesty; prompt, personal service and a desire to put the client’s welfare first and

missing in this day and age: integrity; honesty; prompt, personal service and a desire to put the client’s welfare first and foremost.

We are ranked as top volume brokers with several carriers and with our experience and commitment to quality, have generated significant persuasive influence among the insurance companies to best provide what our insureds need. This has been particularly useful for our clients with special evidence and endorsement forms needed to sustain and grow their business. If it CAN be done, it WILL be done!

All of our agents attend insurance education classes regularly and most have attained insurance industry educational certification designations, i.e. CIC (Certified Insurance Counselor) CISR (Certified Insurance Service Representative) and other accreditations.

Lisa Greenberg

Lisa Greenberg is Founder and President of Cornerstone Specialty Insurance Services, Inc., and provides insurance counseling and risk management to her clients along with a broad range of products and services.

Lisa began her career as a State Farm agent in 1983; at that time she concentrated on personal lines insurance for individuals. In 1985, Lisa transitioned to her specialization in dealing with the complex needs of design professionals and the construction industry. With over three decades of experience, Lisa has the expertise to find the appropriate insurance programs in the market place for a wide variety of businesses

This includes her ability to negotiate highly competitive rates with almost all the leading insurance companies. Lisa also provides risk management, contract review, and seminars for her clients.

Lisa has earned the designation of Certified Insurance Counselor (CIC), the insurance industry’s premier source for practical, real world education for insurance professionals since 1969.

A Southern California native, Lisa lives in Orange County with her family. She is an avid soccer fan, enjoys boating and the outdoors.

Tina Cowie

Tina Cowie is Vice President of Cornerstone Specialty Insurance Services, Inc. She began her career in 1978 as a file clerk for a major insurance company and rapidly advanced to the role of Assistant Personal Lines Underwriter. In 1980, Tina moved to the agency side of the business; she has been Vice President of Cornerstone since 2003.

With over three decades of insurance experience, Tina has the ability to understand and evaluate the insurance needs of various types of businesses, from auto repair shops to architecture firms. Tina Cowie has earned the designations of Customer Insurance Service Representative (CISR), Accredited Customer Service Representative (ACSR) and Certified Insurance Counselor (CIC).

Tina is a Southern California native. She and her husband, John, have been married since 1979 and have three wonderful sons.

Aimee Guesno

Aimee (La Rue) Guesno is an Account Executive at Cornerstone Specialty Insurance Services, Inc., where she began her insurance career in 2004. She has earned the designations of Certified Insurance Counselor (CIC) in 2012 and Certified Insurance Service Representative (CISR) in 2006.

She was born and raised in California and loves her home here. Aimee has been happily married since 2016. She enjoys performing improv of all kinds, is a lover of music, has lots of fun cooking and baking for her family and friends, and relaxes after a long day of insurance by snuggling with her cat Guinevere.

Sue Lusic

Sue Lusic is an account executive and began working at Cornerstone Specialty Services, Inc. in 2012. Her previous career was an elementary school teacher. Sue has been involved in the construction industry her whole life, as her entire family works in construction.

She is a California native, has been married to Rudy since 1977, has three grown children and four grandchildren.


Cornerstone is proud to maintain affiliations with several prominent organizations, whether through sponsorship, membership, consulting work, or other types of specialized support.


Architects & Engineers

Cornerstone Specialty Insurance Services, Inc. is dedicated to assisting design professionals with their insurance and risk management needs. This specialization only adds to the depth of service and savings enjoyed by our clients.

A few of the specialty insurance products we offer to our design professional clients are:

  • Professional Liability
  • Directors & Officers Liability
  • Employment Practices Liability
  • General Liability
  • Cyber Liability
  • Project Policies
  • Railroad Protective Liability
  • Fiduciary
  • Crime
Commercial Lines

The insurance needs of any business are complex. The experienced staff at Cornerstone can help you determine which business insurance policies will best protect and serve the needs of your firm.

Some of these insurance products are:

  • Business Auto Insurance
  • Business Owners Policy (BOP)
  • Commercial Package
  • Contractors Wrap
  • Earthquake Insurance
  • Flood Insurance
  • Excess & Surplus Lines
  • Excess & Commercial Umbrella Policy
  • Inland Marine
  • Property Insurance
  • Workers’ Compensation
  • Drone Coverage
  • Sexual Abuse & Misconduct
Personal Lines

Cornerstone also caters to the needs of individuals seeking appropriate insurance coverage. A few of the Personal Lines insurance products we provide are:

  • Auto Insurance (Preferred & Non-Standard)
  • Condo Owners Insurance
  • Dwelling Fire Insurance
  • Earthquake Insurance
  • Flood Insurance
  • Homeowners Insurance
  • Package Policies
  • Recreational Vehicles
    • – RVs
    • – ATVs
    • – Motorcycles
  • Renter’s Insurance
  • Umbrella
Individual Life & Group Health Benefits

Individual Life & Group Health Benefits coverages are important, and they can also be complex. Let us assist you with a variety of products, including:

  • Group Medical
  • Group Dental
  • Group Life
  • Individual Health Insurance
  • Individual Life Insurance

These are not an exhaustive lists. If you have questions about a product or policy you do not see mentioned here, give us a call.

We are eager to assist you.

of Insurance


At CSIS, we understand how important quick, accurate certificates of insurance are to the day-to-day running of your business.

Cornerstone prepares Certificates of Insurance for all parties doing business with our clients. Original certificates are mailed to the requesting certificate holder within 24 hours unless special provisions are required. Copies are provided to clients for reference.



Online Certificate Issuance

Online certificate issuance & Auto I.D cards. We are pleased to offer our clients the opportunity to issue Auto I.D. cards and some certificates on their own. Clients may use our Client Portal 24/7 as needed.

Request Certificates

Download our Certificate
Request Form



Longtime professional liability provider Victor O. Schinnerer & Co. provided this video describing why an architect or engineer needs professional liability insurance

What is Workers’ Compensation Insurance?
What is Workers’ Compensation Insurance?

The Hartford’s quick e-learning guide to Workers’ Compensation coverage will answer those questions frequently asked by so many business owners: What does Work Comp cover? Why do I need it? Who covers it? Where can I buy it? How much will it cost?

The ProNet Blog
The ProNet Blog

Longtime advocate for architects, engineers, and consultants, a/e ProNet launched their blog this year. Their mission is to reach as many design professionals as possible with ProNet’s comprehensive offering of Insurance, Advice, Advocacy, Risk Management and Continuing Education resources.

Zurich Risk Management Guide
Zurich Risk Management Guide

A resource offered by Zurich American Insurance Company, this guide offers advice about everything from Accesibility and Advertising to Waivers and Warranties.