Exhibit 99.1

FOR IMMEDIATE RELEASE

Deltek Reports Q3 Total Revenue of $85.2 Million, up 31% from Q3 2010

Product Revenue $26.7 million, up 71% from prior year and 8% from Q2

Non-GAAP Operating Income increases 98% from prior year, Margins increase to 19%

HERNDON, Va. – October 26, 2011 – Deltek, Inc. (Nasdaq: PROJ), the leading global provider of enterprise software and information solutions for professional services firms and government contractors, today announced financial results for the quarter ended September 30, 2011.

Q3 product revenue was $26.7 million, up 71% from Q3 2010 and up 8% sequentially. Product revenue includes perpetual, subscription, SaaS and term license revenues. Total revenue for Q3 was $85.2 million, an increase of 31% from $65.2 million in the third quarter of 2010.

Q3 product bookings were $29.5 million, a 9.3% increase from the prior quarter and a 74% increase from the third quarter of 2010. Product bookings consist of the aggregate contract value of the company’s perpetual, subscription, SaaS and term licenses sold during the quarter.

Q3 perpetual license revenue was $15.8 million, an increase of 2.6% from the prior year. Q3 subscription and term license revenue was $10.9 million. Maintenance revenue in the third quarter was $40.5 million, up from $33.9 million in the third quarter of 2010, an increase of 19.4%. Consulting and other revenue for Q3 was $18 million, up 14.5% compared to $15.7 million in Q3 2010.

Q3 GAAP operating income was $5.4 million, compared to a GAAP operating loss of $1.3 million in the prior year.

Non-GAAP operating income for the third quarter of 2011 was $16.2 million, compared to $8.2 million in Q3 2010, an increase of 98%. The Non-GAAP results exclude the purchase accounting impacts and costs associated with the Company’s recent acquisitions, including acquisition-related costs, restructuring charges and incremental intangible asset-related amortization expense.

Q3 GAAP operating margin was 6.3%, compared to a GAAP operating margin of (2%) in Q3 2010.

Q3 Non-GAAP operating margin was 19%, compared to 13% in Q3 2010.

Q3 GAAP net income was $3.1 million, or $0.05 per diluted share, compared to a net loss of $4.1 million, or ($0.06) per diluted share, in Q3 2010.

Non-GAAP net income for the third quarter of 2011 was $9.7 million, or $0.15 per diluted share, compared to $4.3 million, or $0.06 per diluted share, in Q3 2010.

“We had another excellent quarter, highlighted by expanding profits and accelerating margins, and by strong results in the GovCon market,” said Kevin Parker, president and CEO of Deltek. “Our growing portfolio of solutions and flexible product delivery models also contributed to our Q3 success.

“Our strong presence in our core markets and recent acquisitions have clearly added to our capabilities and strengthened our competitive position globally. Q3 product bookings are also a very positive indicator of the continuing success of our broader solutions portfolio.”

Comparison of GAAP and Non-GAAP Measurements:

Non-GAAP operating income and margin exclude the pre-tax impact of stock-based compensation, amortization of acquired intangible assets, purchase accounting impacts relating to acquisitions, acquisition-related costs and restructuring charges. Non-GAAP net income excludes the same items on a net-of-tax basis.

A reconciliation of GAAP to non-GAAP financial measures is provided in the tables at the end of this press release.

Recent Highlights

Conference Call Information

Deltek will host a conference call at 5:00 p.m. Eastern Time today to discuss the Company’s third quarter results. The dial-in number for the conference call is 1-877-381-6419 in North America and 1-706-643-9496 outside North America (passcode: 18426391). The conference call also can be accessed through the Investor Relations section of Deltek’s website (http://investor.deltek.com). Those unable to participate in the live call may hear a replay through November 2, 2011 by dialing 1-855-859-2056 in North America and 1-404-537-3406 outside North America (passcode: 18426391). The replay also will be available through November 9, 2011 on Deltek’s website.

About Deltek

Deltek (Nasdaq: PROJ) is the leading global provider of enterprise software and information solutions for professional services firms and government contractors. For decades, we have delivered actionable insight that empowers our customers to unlock their business potential. Over 14,500 organizations and 1.8 million users in approximately 80 countries around the world rely on Deltek to research and identify opportunities, win new business, optimize resources, streamline operations, and deliver more profitable projects. Deltek – Know more. Do more.^® www.deltek.com

Use of Non-GAAP Financial Measures

This press release and the related conference call described above contain certain non-GAAP financial measures, including non-GAAP net income, non-GAAP operating income and margin, adjusted EBITDA, and non-GAAP revenue. The Company defines non-GAAP net income as GAAP net income (loss) before the net-of-tax impact of stock-based compensation, amortization of acquired intangible assets, purchase accounting impacts relating to acquisitions, acquisition-related costs and restructuring charges. Non-GAAP operating income and margin is defined as GAAP operating income (loss) before the pre-tax impact of stock-based compensation, amortization of acquired intangible assets, purchase accounting impacts relating to acquisitions, acquisition-related costs and restructuring charges. Adjusted EBITDA is defined as GAAP net income (loss) before interest expense (net of interest income), provision for income taxes, depreciation, stock-based compensation, amortization, purchase accounting impacts relating to acquisitions, acquisition-related costs and restructuring charges. Non-GAAP revenue is defined as revenue before the net impact of acquisition-related fair value adjustments to deferred revenue.

The Company believes that the presentation of these measures provides useful information to its investors and lenders because these measures allow for more accurate comparisons of results from period-to-period, enhance the overall understanding of the Company’s performance and provide greater insight into the prospects for the Company’s ongoing business operations. Moreover, the Company also believes it is appropriate to exclude costs associated with restructuring charges because these charges are excluded from management’s assessment of the Company’s operating performance and are not related to the Company’s ongoing business operations. In addition, the Company excludes the items from EBITDA described above in its calculations to determine compliance with its debt covenants and to assess its ability to borrow additional funds to finance or expand its operations.

The Company believes that by reporting these measures, it provides insight and consistency in its financial reporting and presents a basis for comparison of its business operations between current, past and future periods. In addition, the measures provide a basis for the Company to compare its financial results to those of other comparable publicly traded companies and are used by its management team to plan and forecast its business.

Non-GAAP financial measures should not be considered as a substitute for, or superior to, measures of financial performance which are prepared in accordance with U.S. GAAP and may be different from non-GAAP financial measures used by other companies. Investors are encouraged to review the reconciliations of our GAAP to non-GAAP net income, operating income and margin, adjusted EBITDA and revenue, which are set forth below.

Forward-Looking Statements

This press release and related conference call contain forward-looking statements that involve substantial risks and uncertainties. You can identify forward-looking statements by words such as “anticipate,” “believe,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “should,” “would” or similar words. You should consider these statements carefully because they discuss our plans, targets, strategies, prospects and expectations concerning our business, operating results, financial condition and other similar matters. We believe that it is important to communicate our future expectations to our investors. There will be events in the future,

however, that we are not able to predict accurately or control. Our actual results may differ materially from the expectations we describe in our forward-looking statements. Factors or events that could cause our actual results to materially differ may emerge from time to time, and it is not possible for us to accurately predict all of them. Before you invest in our common stock, you should be aware that the occurrence of any such event or of any of the additional events described as risk factors in the Company’s filings with the Securities and Exchange Commission could have a material adverse effect on our business, results of operation and financial position. Any forward-looking statement made by us in this press release or related conference call speaks only as of the date on which we make it. We undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law.

DELTEK, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands, except per share data)

(unaudited)

DELTEK, INC.

CONSOLIDATED BALANCE SHEETS

(in thousands, except share data)

(unaudited)

DELTEK, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands)

(unaudited)

DELTEK, INC.

RECONCILIATION OF GAAP NET INCOME (LOSS) TO NON-GAAP NET INCOME

(in thousands, except per share data)

(unaudited)

RECONCILIATION OF GAAP OPERATING INCOME (LOSS) AND OPERATING MARGIN (DEFICIT) TO NON-GAAP

OPERATING INCOME AND OPERATING MARGIN

(in thousands)

(unaudited)

RECONCILIATION OF GAAP NET INCOME (LOSS) TO ADJUSTED EBITDA

(in thousands)

(unaudited)

REVENUES

(in thousands)

(unaudited)

STOCK-BASED COMPENSATION EXPENSE

(in thousands)

(unaudited)

AMORTIZATION OF ACQUIRED INTANGIBLE ASSETS

(in thousands)

(unaudited)

AMORTIZATION AND DEPRECIATION EXPENSES

(in thousands)

(unaudited)