UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORTPURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): July 20, 2006

HILL INTERNATIONAL, INC.(Exact Name of Registrant as Specified in Charter)

Delaware 000-50781 20-0953973(State or Other Jurisdiction

of Incorporation) (Commission

File Number) (IRS Employer

Identification No.)

303 Lippincott Centre, Marlton, NJ 08053(Address of Principal Executive Offices) (Zip Code)

Registrant’s telephone number, including area code: (856) 810-6200

Arpeggio Acquisition Corporation(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the followingprovisions (see General Instruction A.2. below):

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Item 1.01 Entry into a Material Definitive Agreement.

On July 20, 2006, Hill International SA, a wholly-owned subsidiary of Hill International, Inc. (the “Registrant”) entered into material definitiveagreements not made in the ordinary course of business with the directors and certain affiliates of James R. Knowles (Holdings) PLC (“Knowles”) to acquireapproximately 69.4% of the outstanding shares of Knowles for a price of 33 pence (approximately $0.61) per share in cash. Knowles is a construction andengineering industry claims consulting and dispute resolution company with 36 offices worldwide, headquartered in Daresbury, United Kingdom. At the sametime, the boards of directors of both the Registrant and Knowles approved the terms of a cash offer by Hill International SA for all of the issued shares ofKnowles at a price of 33 pence (approximately $0.61) per share. This offer values Knowles at approximately $13.0 million.

In addition, on July 20, 2006, Hill International SA entered into agreements with other shareholders of Knowles to acquire approximately 10.6% ofthe outstanding shares of Knowles for a price of 33 pence (approximately $0.61) per share in cash, subject to the contingency that such agreements will ceaseto be binding if those Knowles shareholders receive a competing offer for their Knowles shares at a price that is greater than 36.3 pence (approximately$0.67) per share.

The agreements are subject to a number of conditions to closing typical for agreements of this kind, including, without limitation, that HillInternational SA receive no less than 80% of the outstanding shares of Knowles, or such lower percentage as Hill may determine while the offer isoutstanding.

Copies of the agreements between Hill International SA, the Registrant and Knowles are attached as exhibits to this Current Report. On July 21,2006, the Registrant issued a press release announcing the cash offer by Hill International, SA for the shares of Knowles and the execution of theaforementioned agreements between the Registrant, Hill International SA and certain of the shareholders of Knowles. A copy of the press release is attachedhereto as an exhibit.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit No. Description10.1 Irrevocable Undertaking, dated July 20, 2006, to Hill International SA, Hill International, Inc. and Ernst & Young LLP from

Active Capital Trust PLC. 10.2 Director’s Irrevocable Undertaking, dated July 20, 2006, to Hill International SA, Hill International, Inc. and Ernst & Young

LLP from Lord Lee of Trafford. 10.3 Irrevocable Undertaking, dated July 20, 2006, to Hill International SA, Hill International, Inc. and Ernst & Young LLP from

Michael Conrad Charlton.

10.4 Director’s Irrevocable Undertaking, dated July 20, 2006, to Hill International SA, Hill International, Inc. and Ernst & Young

LLP from Peter Bates. 10.5 Irrevocable Undertaking, dated July 20, 2006, to Hill International SA, Hill International, Inc. and Ernst & Young LLP from

White Rose Nominees Limited. 10.6 Director’s Irrevocable Undertaking, dated July 20, 2006, to Hill International SA, Hill International, Inc. and Ernst & Young

LLP from Roger Knowles. 10.7 Director’s Irrevocable Undertaking, dated July 20, 2006, to Hill International SA, Hill International, Inc. and Ernst & Young

LLP from Wendy Knowles. 10.8 Irrevocable Undertaking, dated July 20, 2006, to Hill International SA, Hill International, Inc. and Ernst & Young LLP from

Wynton Services Limited. 10.9 Director’s Irrevocable Undertaking, dated July 20, 2006, to Hill International SA, Hill International, Inc. and Ernst & Young

LLP from Brian Stephen Quinn. 99.1 Press release of the Registrant dated July 21, 2006.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by theundersigned hereunto duly authorized. Dated: July 26, 2006 HILL INTERNATIONAL, INC.

By: /s/ Irvin E. Richter

Name: Irvin E. RichterTitle: Chairman and Chief Executive Officer

Hill International to Acquire James R. Knowles (Holdings) PLC MARLTON, N.J., Jul 21, 2006 (BUSINESS WIRE) -- Hill International, Inc. (Nasdaq:HINT), the worldwide construction consulting firm, announced todaythat the boards of directors of Hill and James R. Knowles (Holdings) PLC (LSE:JRK.L), a United Kingdom-based firm that provides technical consulting anddispute resolution services to the engineering and construction industry worldwide, have unanimously approved the terms of a recommended cash offer to bemade by a wholly-owned subsidiary of Hill for all of the issued shares of Knowles at a price of 33 pence ($0.61) per share in cash. Hill's offer values all of theissued shares of Knowles at approximately GBP 7.0 million ($13.0 million). The last trading price of Knowles' shares yesterday on the AIM market of the London Stock Exchange was 29.5 pence per share. The shares have traded in a52-week range of between 20 and 37.5 pence. Hill has already received commitments from the holders of 16,953,750 Knowles shares (or approximately 80.08% of Knowles' 21,171,853 issued shares) thatthey will be tendered to Hill in response to the offer. Of those shares, 14,702,375 Knowles shares (or approximately 69.44% of all issued shares) are held byKnowles' directors and affiliated parties and one further shareholder, and must be tendered to Hill regardless of any possible competing offer. The remainingcommitments, for a further 2,251,375 Knowles shares (or approximately 10.63% of all issued shares), will cease to be binding if a competing offer is madefor Knowles shares at a price per share that is more than 10% higher than Hill's offer. Hill's offer is conditioned upon, inter alia, receiving no less than 80% of all of Knowles issued shares, or such lower percentage as Hill may determine duringthe offer. With 75% or more of Knowles shares tendered, application may be made, subject to certain conditions, for the cessation of the trading of Knowlesshares from the AIM market of the London Stock Exchange. With 90% or more of Knowles shares tendered, Hill may acquire on a compulsory basis anyremaining Knowles shares on the same terms as the offer. For its financial year ended July 31, 2005, Knowles reported turnover, or revenue, of GBP 30.2 million ($55.9 million), as compared to GBP 31.3 million($57.9 million) for the same period in 2004, and profit before taxation of GBP 41,000 ($76,000) in 2005 as compared to GBP 486,000 ($899,000) in 2004. Asof July 31, 2005, Knowles had net assets, or shareholders' equity, of GBP 4.6 million ($8.5 million). For the six months ended January 31, 2006, Knowles' unaudited results consisted of turnover of GBP 14.9 million ($27.6 million), as compared to GBP 14.7million ($27.2 million) for the same period in 2005, and a loss before taxation of GBP 391,000 ($723,000) for such 2006 period, as compared to a profitbefore taxation of GBP 44,000 ($81,000) for the same period in 2005. As of January 31, 2006, Knowles had net assets of GBP 4.3 million ($8.0 million). Hill's management believes that numerous synergies exist between the companies and anticipates that consolidation benefits will be achieved within theenlarged group. Hill also expects that cost savings can be realized from the combination of the two companies. Specifically, cost savings are expected fromthe cessation of trading of Knowles shares on the AIM market of the London Stock Exchange and also Knowles' Executive Chairman, J. Roger Knowles, hasagreed to resign upon consummation of the transaction and he is not expected to be replaced. It is anticipated that Brian S. Quinn, Knowles' Chief ExecutiveOfficer, and Charlotte L. Parsons, Knowles' Finance Director, will remain with the company following its acquisition by Hill. Irvin E. Richter, Hill's Chairman and Chief Executive Officer, stated, "Knowles has earned an enviable reputation in the worldwide construction claimsindustry, and created an impressive network of strategic office locations around the world. We believe that Knowles offers Hill a unique and cost-effectiveopportunity to enter new geographic markets, strengthen our position in overlapping locations, and capture a global leadership position in construction claims.The combination of our firms also gives us the opportunity to broaden the services Knowles offers to its clients as a result of Hill's expertise in constructionproject management."

J. Roger Knowles, founder and Executive Chairman of Knowles, stated, "When we began the process of seeking a strategic buyer for my stake in Knowles inDecember 2005, our strategic objectives were to maximize shareholder value and find a buyer that would uphold the reputation and relationships that we havedeveloped over the last 33 years. I believe that both of those objectives have been achieved. Hill and Knowles share a similar, results-based, customer-centriccorporate culture, a complementary suite of service offerings, and considerable global market coverage. As a result, I expect a smooth integration of ourbusinesses." In connection with this transaction, Knowles is being advised by Brewin Dolphin Securities Ltd. and the law firm of Halliwells LLP. Hill is being advised byErnst & Young LLP and the law firm of Taylor Wessing. Knowles, headquartered in Daresbury, UK, provides technical consulting and dispute resolution services to the engineering and construction industryworldwide. Knowles' nearly 350 employees operate out of 36 offices in the United Kingdom, Western Europe, the Middle East, Southeast Asia, Australia,Canada and the United States. For more information on Knowles, please visit their website at www.jrknowles.com. Hill International, with over 1,000 employees in 26 offices worldwide, provides program management, project management, construction management, andconstruction claims services. Engineering News-Record magazine recently ranked Hill as the 17th largest construction management firm in the United States.For more information on Hill, please visit our website at www.hillintl.com. This press release includes certain statements that fall within the definition of "forward-looking statements" under the Private Securities Litigation ReformAct of 1995. Any such statements are subject to risks and uncertainties, overall economic and market conditions, competitors' and clients' actions, andweather conditions, which could cause actual results to differ materially from those anticipated, including those risks identified in Hill's filings with theSecurities and Exchange Commission. Accordingly, such statements should be considered in light of these risks. Any prediction by Hill is only a statement ofmanagement's belief at the time the prediction is made. There can be no assurance that any prediction once made will continue thereafter to reflectmanagement's belief, and Hill does not undertake to update publicly its predictions, whether as a result of new information, future events or otherwise. AllU.S. dollar amounts contained in this press release are based upon exchange rates as of July 20, 2006. (HINT-G) SOURCE: Hill International, Inc. Hill International, Inc.John P. Paolin, 856-810-6210johnpaolin@hillintl.comorThe Equity Group Inc.Devin Sullivan, 212-836-9608 Copyright Business Wire 2006 News Provided by COMTEX