Exhibit 99.1

WILLIAM LYON HOMES REPORTS SECOND QUARTER 2018 RESULTS

30% INCREASE IN NEW HOME DELIVERIES; 25% INCREASE IN NET NEW HOME ORDERS;

140 BASIS POINT INCREASE IN GAAP GROSS MARGINS; 22% INCREASE IN ADJUSTED NET INCOME

NEWPORT BEACH, CA— July 31, 2018 — William Lyon Homes (NYSE: WLH), a leading homebuilder in the Western U.S., announced results for its second quarter ended June 30, 2018.

2018 Second Quarter Highlights (Comparison to 2017 Second Quarter)

“We are pleased with our financial results for the second quarter, with several key metrics up over the prior year, including homebuilding revenues of $518.4 million, up 23%, new home deliveries of 1,082, up 30%, adjusted pre-tax income of $35.8 million, up 21%, adjusted net income of $23.1 million, up 22%, and adjusted earnings per share on a diluted basis of $0.58, up 18%,” said Matthew R. Zaist, President and Chief Executive Officer. “During the quarter, our GAAP homebuilding gross margins were 17.9%, including purchase accounting adjustments from the RSI acquisition, up 140 basis points compared to the second quarter of 2017, and up 40 basis points sequentially from the first quarter of this year.”

Mr. Zaist continued, “We also delivered another quarter of year-over-year improvement in net new home orders, which increased 25% to 1,270, and represents a monthly absorption rate of 4.0 net new home orders per community compared to 3.9 in the year ago period. The increase in monthly absorption rate year-over-year was driven by an improvement in both May and June absorption rates.”

Mr. Zaist added, “The strong performance in the first half of 2018 positions us well to achieve our goals for the year, and our updated expectations for the full year include new home deliveries of approximately 4,400 to 4,700 units, home sales revenue of approximately $2.25 billion to $2.35 billion, and pre-tax income before non-controlling interest of approximately $175 million to $185 million.”

Operating Results

Home sales revenue for the second quarter of 2018 was $518.4 million, as compared to $422.6 million in the year-ago period, an increase of 23%. The increase was driven by a 30% increase in deliveries to 1,082 homes, compared to 831 in the second quarter of 2017.

The dollar value of orders for the second quarter of 2018 was $623.1 million, an increase of 12%, from $554.0 million in the year-ago period. Net new home orders for the quarter were 1,270, up 25% from 1,017 in the second quarter of 2017, which represents monthly absorption of 4.5 per community in April, 3.3 in May compared to 3.2 in the prior year, and 4.0 in June compared to 3.5 in the prior year.

The dollar value of homes in backlog was $867.7 million as of June 30, 2018, an increase of 15%, compared to $755.3 million as of June 30, 2017. The increase was driven by a 28% increase in units in backlog to 1,648 from 1,285 in the year-ago period. The average sales price of homes in backlog decreased to $526,500 from $587,800 in the prior year, due to a higher number of homes in backlog from entry level buyers, which represent 48% of homes in backlog. In addition, our ASP in backlog as of June 30, 2018 was 10% higher than the ASP of homes closed in the second quarter.

Homebuilding gross margin percentage for homes closed during the second quarter of 2018 was 17.9%, up 140 basis points from 16.5% in the second quarter of 2017, and up 40 basis points from 17.5% in the first quarter of 2018.

Sales and marketing expense during the second quarter of 2018 was 5.6% of homebuilding revenue, compared to 5.0% in the year-ago quarter, which is primarily driven by the impact of the adoption of ASC 606, which was adopted on January 1, 2018, requiring the Company to record certain selling costs that were previously recorded as cost of sales to sales and marketing expense. General and administrative expenses increased to 5.5% of homebuilding revenue, compared to 4.6% in the year-ago quarter due to an increased headcount as a result of the RSI acquisition.

Balance Sheet Update

At quarter end, cash and cash equivalents totaled $49.2 million, owned real estate inventories totaled $2.3 billion, total assets were $2.9 billion and total equity was $981.0 million. Total debt to book capitalization was 59.5%, and net debt to net book capitalization was 58.6% at June 30, 2018, compared to 57.9% and 57.2% at June 30, 2017, and 54.5% and 49.6% at December 31, 2017, respectively.

During the second quarter the Company closed on a new credit agreement providing for an unsecured revolving credit facility of up to $325 million, which replaces the Company’s previous $170 million revolving credit facility.

Conference Call

The Company will host a conference call to discuss these results today, Tuesday, July 31, 2018 at 9:00 a.m. Pacific Time. The call will be available via both the telephone at (855) 851-4524 or (720) 634-2900, conference ID # 5673637, 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 August 7, 2018 by dialing (855) 859-2056 or (404) 537-3406, conference ID #5673637. 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, Oregon, and Texas. Its core markets include Orange County, Los Angeles, the Inland Empire, the San Francisco Bay Area, Phoenix, Las Vegas, Denver, Portland, Seattle, Austin and San Antonio. The Company has a distinguished legacy of more than 60 years of homebuilding operations, over which time it has sold in excess of 104,000 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 pre-tax income, gross margin performance, backlog conversion rates, operating and financial results for the third quarter of 2018 and full year 2018 and beyond, 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, minority interest from our homebuilding joint ventures, leverage ratios and reduction strategies, land acquisition spending, financial services and ancillary business performance and strategies; the anticipated benefits to be realized from the RSI acquisition; the anticipated financial or operational performance resulting from the RSI Communities transaction, and estimated new home deliveries, home sales revenue and community count on a combined Company basis. 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: the Company’s ability to successfully integrate RSI Communities’ homebuilding operations with its existing operations; any adverse effect on the Company’s, or RSI Communities’, business operations following the acquisition; 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 housing supply in our markets; affordability pressures; increased outside broker costs; increased costs of homebuilding materials; changes in governmental laws and regulations and compliance, increased costs, fees and delays associated therewith; government actions, policies, programs and regulations directed at or affecting the housing market (including the Tax Cuts and Jobs Act (“TCJA”), the Dodd-Frank Act, tax benefits associated with purchasing and owning a home, and the standards, fees and size limits applicable to the purchase or insuring of mortgage loans by government-sponsored enterprises and government agencies), the homebuilding industry, or construction activities; changes in existing tax laws or enacted corporate income tax rates, including pursuant to the TCJA; 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; defects in manufactured products or other homebuilding materials; decline in real estate values resulting in impairment of our real estate assets; volatility in the banking industry, credit and capital markets; restraints on foreign investment; terrorism or other hostilities involving the United States and other geopolitical risk as well as restrictive policies such as tariffs or capital investment restrictions; 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; 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

(in thousands except number of shares and per share data)

(unaudited)

WILLIAM LYON HOMES

CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands except number of shares and per share data)

(unaudited)

WILLIAM LYON HOMES

CONSOLIDATED BALANCE SHEETS

(in thousands, except number of shares and par value per share)

WILLIAM LYON HOMES

SELECTED FINANCIAL AND OPERATING INFORMATION

(unaudited)

WILLIAM LYON HOMES

SELECTED FINANCIAL AND OPERATING INFORMATION

(unaudited)

WILLIAM LYON HOMES

SELECTED FINANCIAL AND OPERATING INFORMATION

(unaudited)

WILLIAM LYON HOMES

SUPPLEMENTAL FINANCIAL INFORMATION

(dollars in thousands)

(unaudited)

Balance Sheet Data

WILLIAM LYON HOMES

SUPPLEMENTAL FINANCIAL INFORMATION

(dollars in thousands)

(unaudited)

WILLIAM LYON HOMES

SUPPLEMENTAL FINANCIAL INFORMATION

(dollars in thousands)

(unaudited)

WILLIAM LYON HOMES

SUPPLEMENTAL FINANCIAL INFORMATION

(dollars in thousands)

(unaudited)

Adjusted pre-tax income means income before provision for income taxes plus transaction expenses and loss for the extinguishment of the 8.5% Senior Notes. Adjusted pre-tax income is not a financial measure prepared in accordance with U.S. GAAP. Adjusted pre-tax income is presented herein because management believes the presentation of adjusted pre-tax income provides useful information to the Company’s investors regarding the Company’s results of operations because adjusted pre-tax income isolates the impact of the one-time, non-recurring transaction expenses and infrequent extinguishment fees. Adjusted pre-tax income should not be considered as an alternative for net income, cash flows from operating activities and other consolidated income or cash flow statement data prepared in accordance with accounting principles generally accepted in the United States or as a measure of profitability or liquidity. A reconciliation of income before provision for income taxes to adjusted pre-tax income is provided in the following table: