Exhibit 99.1

WILLIAM LYON HOMES REPORTS FIRST QUARTER 2017 RESULTS

26% INCREASE IN NET NEW HOME ORDERS; DOLLAR VALUE OF ORDERS UP 35%;

19% INCREASE IN AVERAGE COMMUNITY COUNT; 34% INCREASE IN DOLLAR VALUE OF BACKLOG

NEWPORT BEACH, CA— May 9, 2017 — William Lyon Homes (NYSE: WLH), a leading homebuilder in the Western U.S., announced results for its first quarter ended March 31, 2017.

2017 First Quarter Highlights (Comparison to 2016 First Quarter)

“We are extremely excited about our sales momentum to start the year, in what has been a robust Spring selling season year-to-date, as well as the early results from the opening of certain of our key strategic assets,” said Matthew R. Zaist, President and Chief Executive Officer. “We have experienced month-over-month improvement in absorption rates through each month of the first quarter, averaging 3.5 sales per community per month. This absorption pace increased through April 2017 to 4.8 sales per month, resulting in 432 net new home orders, an increase of 48% over April 2016. Community count averaged 82 in the first quarter, up 19% year-over-year, increasing to 90 average new home selling communities in the month of April 2017.”

Mr. Zaist continued, “We are pleased with our execution in January in the bond market, allowing the Company to strengthen its balance sheet and refinance its most expensive debt with the issuance of new 5.875% senior unsecured notes due 2025, which will save the Company approximately $10 million in annual interest expense and which extends and further staggers our senior notes maturities. Our adjusted net income for the first quarter was $4.1 million, or $0.11 per diluted share, which was below our expectations primarily due to the timing of the closing of 25 units at one project in California, representing approximately $20 million of revenue and approximately $4.5 million of pre-tax profit, which had been included in our prior guidance for the first quarter and now will be recognized in the second quarter of 2017.”

“Despite a challenging weather and labor environment in a number of our markets, we remain encouraged by our strong start to the Spring selling season, increasing gross margins in backlog, and the successful opening of several key strategic projects that will drive results for the balance of the year, and our full year guidance remains unchanged. For the full year 2017, we continue to expect results to include deliveries of approximately 3,000 to 3,250 units, home sales revenue of approximately $1.65 billion to $1.75 billion, and pre-tax income before non-controlling interest of approximately $135 million to $150 million.”

Operating Results

Home sales revenue for the first quarter of 2017 was $258.9 million, as compared to $261.3 million in the year-ago period, a decrease of 1%. The decline was driven by an 8% decrease in deliveries to 499 homes, compared to 543 in the first quarter of 2016, partially offset by an increase in the average sales price of homes delivered to $518,700, up 8% from the prior year.

The dollar value of homes in backlog was $634.2 million as of March 31, 2017, an increase of 34% compared to $471.7 million as of March 31, 2016. The increase was driven by a 24% increase in units in backlog to 1,099 from 885 in the year-ago period and an 8% increase in ASP in backlog to $577,100 from $533,000 in the first quarter of 2016. In addition, our ASP in backlog as of March 31, 2017 was 11% higher than the ASP of homes closed in the first quarter.

Homebuilding gross margin percentage for homes closed during the first quarter of 2017 was 15.6%. Adjusted homebuilding gross margin percentage for the quarter was 21.1%. Current homebuilding gross margin percentage in backlog is 18%.

Sales and marketing expense during the first quarter of 2017 was 5.7% of homebuilding revenue, consistent with the year-ago quarter. General and administrative expenses were 7.3% of homebuilding revenue, compared to 6.8% in the first quarter of 2016, due in part to a slight increase in G&A expense on a dollar basis and a slight decrease in homebuilding revenue.

Senior Notes Refinancing Transaction

During the first quarter, the Company completed an offering of $450 million in aggregate principal amount of 5.875% Senior Notes due 2025, the proceeds of which were used to repay in full the existing $425 million in principal of 8.5% Senior Notes that were due in 2020. The Company incurred certain costs in the first quarter related to the early extinguishment of debt of the 8.5% Notes, in an amount of approximately $21.8 million on a pre-tax basis, and an amount of approximately $14.1 million on an after-tax basis. The Company anticipates that the lower coupon rate on the new notes will save the Company approximately $10 million per year in interest cost, and the return of cost on the charge, giving effect to the interest savings, is expected to be approximately 17 months. In addition, the new notes will mature in 2025, approximately five years beyond the maturity date of the old notes.

Balance Sheet Update

At quarter end, cash and cash equivalents totaled $39.5 million, real estate inventories totaled $1.8 billion, total assets were $2.0 billion and total equity was $748.6 million. Total debt to book capitalization was 60.1%, and net debt to net book capitalization was 59.2% at March 31, 2017, compared to 61.0% and 60.2% at March 31, 2016, and 58.6% and 57.6% at December 31, 2016, respectively.

Conference Call

The Company will host a conference call to discuss these results today, Tuesday, May 9, 2017 at 8:30 a.m. Pacific Time. The call will be available via both the telephone at (855) 851-4524 or (720) 634-2900, conference ID #10981054, or through the Company’s website at www.lyonhomes.com in the Investor Relations section of the site.

A replay of the call will be available through May 16, 2017 by dialing (855) 859-2056 or (404) 537-3406, conference ID #10981054. A webcast replay of the call will also be available on the Company’s website approximately two hours after the broadcast.

About William Lyon Homes

William Lyon Homes is one of the largest Western U.S. regional homebuilders. Headquartered in Newport Beach, California, the Company is primarily engaged in the design, construction, marketing and sale of single-family detached and attached homes in California, Arizona, Nevada, Colorado, Washington and Oregon. Its core markets include Orange County, Los Angeles, the Inland Empire, the San Francisco Bay Area, Phoenix, Las Vegas, Denver, Portland and Seattle. The Company has a distinguished legacy of more than 60 years of homebuilding operations, over which time it has sold in excess of 99,000 homes. The Company markets and sells its homes under the William Lyon Homes brand in all of its markets except for Washington and Oregon, where the Company operates under the Polygon Northwest brand.

Forward-Looking Statements

Certain statements contained in this release and the accompanying comments during our conference call that are not historical information may constitute “forward-looking statements” as defined by the Private Securities Litigation Reform Act of 1995, including, but not limited to, forward-looking statements related to: anticipated new home deliveries, revenue and pre-tax income, gross margin performance, backlog conversion rates, operating and financial results for the second quarter of 2017 and full year 2017, community count growth and project performance, market and industry trends, the continued housing market recovery, average sale price of homes to be closed in various periods, SG&A percentage, future cash needs and liquidity, leverage ratios and reduction strategies and land acquisition spending. The forward-looking statements involve risks and uncertainties and actual results may differ materially from those projected or implied. The Company makes no commitment, and disclaims any duty, to update or revise any forward-looking statements to reflect future events or changes in these expectations. Further, certain forward-looking statements are based on assumptions of future events which may not prove to be accurate. Factors that may impact such forward-looking statements include, among others: adverse weather conditions; the availability of labor and homebuilding materials and increased

construction cycle times; the availability and timing of mortgage financing; our financial leverage and level of indebtedness and any inability to comply with financial and other covenants under our debt instruments; continued volatility and worsening in general economic conditions either internationally, nationally or in regions in which we operate; increased outside broker costs; increased costs of homebuilding materials; changes in governmental laws and regulations and increased costs, fees and delays associated therewith; potential changes to the tax code; worsening in markets for residential housing; the impact of construction defect, product liability and home warranty claims, including the adequacy of self-insurance accruals, and the applicability and sufficiency of our insurance coverage; decline in real estate values resulting in impairment of our real estate assets; volatility in the banking industry, credit and capital markets; terrorism or other hostilities involving the United States; building moratorium or “slow-growth” or “no-growth” initiatives that could be implemented in states in which we operate; changes in mortgage and other interest rates; conditions in the capital, credit and financial markets, including mortgage lending standards and the availability of mortgage financing; changes in generally accepted accounting principles or interpretations of those principles; changes in prices of homebuilding materials; competition for home sales from other sellers of new and resale homes; cancellations and our ability to realize our backlog; the occurrence of events such as landslides, soil subsidence and earthquakes that are uninsurable, not economically insurable or not subject to effective indemnification agreements; limitations on our ability to utilize our tax attributes; whether an ownership change occurred that could, under certain circumstances, have resulted in the limitation of our ability to offset prior years’ taxable income with net operating losses; the timing of receipt of regulatory approvals and the opening of projects; the availability and cost of land for future development; and additional factors discussed under the sections captioned “Risk Factors” included in our annual and quarterly reports filed with the Securities and Exchange Commission. The foregoing list is not exhaustive. New risk factors may emerge from time to time and it is not possible for management to predict all such risk factors or to assess the impact of such risk factors on our business.

Investor/Media Contacts:

Larry Clark

Financial Profiles, Inc.

(310) 622-8223

WLH@finprofiles.com

WILLIAM LYON HOMES

CONSOLIDATED STATEMENTS OF OPERATIONS

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(unaudited)

WILLIAM LYON HOMES

CONSOLIDATED BALANCE SHEETS

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WILLIAM LYON HOMES

SELECTED FINANCIAL AND OPERATING INFORMATION

(unaudited)

WILLIAM LYON HOMES

SELECTED FINANCIAL AND OPERATING INFORMATION

(unaudited)

WILLIAM LYON HOMES

SUPPLEMENTAL FINANCIAL INFORMATION

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(unaudited)

WILLIAM LYON HOMES

SUPPLEMENTAL FINANCIAL INFORMATION

(dollars in thousands)

(unaudited)

WILLIAM LYON HOMES

SUPPLEMENTAL FINANCIAL INFORMATION

(dollars in thousands)

(unaudited)