Filed pursuant to Rule 424(b)(3)
Registration No. 333-139499

Prospectus Supplement No. 6
(To Prospectus dated May 4, 2007)

4,280,714

SHARES

WILLBROS GROUP, INC.

COMMON STOCK

     This prospectus supplement No. 6 supplements and amends the prospectus dated May 4, 2007, as supplemented and amended by that certain prospectus supplement No. 1 dated May 10, 2007, that certain prospectus supplement No. 2 dated May 17, 2007, that certain prospectus supplement No. 3 dated May 24, 2007, that certain prospectus supplement No. 4 dated May 30, 2007 and that certain prospectus supplement No. 5 dated June 8, 2007 (the “Prospectus”). This prospectus supplement should be read in conjunction with the Prospectus, which is to be delivered with this prospectus supplement.

     There are significant risks associated with an investment in our securities. These risks are described under the caption “Risk Factors” beginning on page 6 of the Prospectus, as the same may be updated in prospectus supplements.

     Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying Prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is August 7, 2007.

Second Quarter 2007 Results from Continuing Operations

     On August 7, 2007, Willbros Group, Inc. (the “Company”) reported its unaudited results from continuing operations for the second quarter of 2007. Revenue from continuing operations for the second quarter of 2007 was $156.7 million, compared to first quarter revenue of $206.7 million. The net loss from continuing operations for the second quarter was $40.4 million or $1.47 per share compared to $3.3 million, or $0.13 per share in the first quarter of 2007. The net loss from continuing operations for the second quarter includes

	•		a charge of $24.0 million in estimated payments relating to settlement discussions with the Department of Justice (“DOJ”) and the Securities and Exchange Commission (“SEC”) and
	•		a charge of $15.4 million relating to the loss on early extinguishment of debt associated with the induced conversion of approximately $52 million of the Company’s 6.5% Senior Convertible Notes due 2012.

     As previously disclosed in January 2005, the Company is under investigation by the DOJ concerning possible violations of the Foreign Corrupt Practices Act and the SEC for possible violations of the Securities Act of 1933 and the Securities Exchange Act of 1934. These investigations stem primarily from the Company’s former operations in Bolivia, Ecuador and Nigeria. The Company is currently engaged in preliminary settlement discussions with both the DOJ and the SEC relating to their investigations. There can be no assurance as to the type and number of charges against the Company in any final resolution of these investigations, nor can there be any assurance regarding the amount of the payments, including fines and penalties, that may be imposed. Although these discussions are still preliminary, the Company recorded a charge of $24.0 million ($0.87 per basic and diluted share) in the second quarter of 2007. This charge represents the Company’s best estimate of the payments necessary to resolve the government investigations. The Company may be required to record an additional provision or reduce this provision if the actual settlement amount of these matters differs from the current provision. The Company anticipates that the terms for these payments will not materially impact the Company’s working capital position or otherwise negatively impact its compliance with debt covenants and other contractual commitments. Although the Company believes that it is moving towards a final resolution of both investigations, it is not possible to predict definitively when final resolution will occur.

WILLBROS GROUP, INC.
(In Thousands, Except Per Share Amounts)

		Three Months Ended								Six Months Ended
		June 30,								June 30,
		2007				2006				2007				2006
Statement of Operations Data
Contract revenue
Construction		$	111,949			$	87,235			$	282,654			$	166,383
Engineering			20,801				19,924				40,456				35,405
EPC			23,993				11,969				40,342				24,927
			156,743				119,128				363,452				226,715
Contract cost
Construction			99,558				78,551				264,562				155,260
Engineering			14,543				15,734				30,132				29,306
EPC			23,768				1,462				37,007				22,644
			137,869				105,747				331,701				207,210
Contract income
Construction			12,391				8,684				18,092				11,123
Engineering			6,258				4,190				10,324				6,099
EPC			225				507				3,335				2,283
			18,874				13,381				31,751				19,505
Depreciation and amortization			4,310				2,924				7,766				5,915
General and administrative			13,422				11,636				24,847				22,041
Government fines and penalties			24,000				—				24,000				—
Operating loss			(22,858	)			(1,179	)			(24,862	)			(8,451	)
Other income (expense):
Interest — net			(187	)			(1,787	)			(1,077	)			(3,423	)
Other — net			(502	)			(452	)			(692	)			(327	)
Loss on early Extinguishment of debt			(15,375	)			—				(15,375	)			—
			(16,064	)			(2,239	)			(17,144	)			(3,750	)
Loss before income taxes			(38,922	)			(3,418	)			(42,006	)			(12,201	)
Provision for income taxes			1,457				1,686				1,712				1,432
Loss from continuing operations		$	(40,379	)		$	(5,104	)		$	(43,718	)		$	(13,633	)
Basic loss per share Continuing operations		$	(1.47	)			(0.24	)			(1.65	)			(0.63	)
		$	(1.47	)			(0.24	)			(1.65	)			(0.63	)
Diluted loss per share Continuing operations		$	(1.47	)			(0.24	)			(1.65	)			(0.63	)
		$	(1.47	)			(0.24	)			(1.65	)			(0.63	)

		Three Months Ended								Six Months Ended
		June 30,								June 30,
		2007				2006				2007				2006
Cash Flow Data
Continuing operations:
Cash provided by (used in):
Operating activities		$	9,743			$	(8,692	)		$	2,403			$	(10,426	)
Investing activities			(25,911	)			3,649				102,877				21,312
Financing activities			(17,907	)			(3,400	)			(22,092	)			11,181
Foreign exchange effects			(636	)			(158	)			(453	)			(118	)
Other Data (Continuing Operations)
Weighted average shares outstanding:
Basic			27,516				21,539				26,505				21,442
Diluted			27,516				21,539				26,505				21,442
EBITDA (2)		$	(34,425	)		$	1,293			$	(33,163	)		$	(2,863	)
Capital expenditures			(8,334	)			(1,594	)			(10,836	)			(5,157	)
Reconciliation of Non-GAAP Financial Measure
EBITDA (2)
Net loss, continuing operations		$	(40,379	)		$	(5,104	)		$	(43,718	)		$	(13,633	)
Interest — net			187				1,787				1,077				3,423
Income taxes			1,457				1,686				1,712				1,432
Depreciation and amortization			4,310				2,924				7,766				5,915
EBITDA		$	(34,425	)		$	1,293			$	(33,163	)		$	(2,863	)

		6/30/2007				3/31/2007				12/31/2006
Balance Sheet Data
Cash and cash equivalents		$	107,762			$	145,439			$	37,643
Working capital			116,426				161,046				170,825
Total assets			406,568				410,714				588,254
Total debt			136,420				167,789				166,152
Stockholders’ equity			102,155				84,569				97,931
Backlog Data (1)
By Reporting Segment:
Construction		$	808,617			$	397,080			$	320,461
Engineering			90,943				92,615				109,122
EPC			144,686				158,594				172,689
		$	1,044,246			$	648,289			$	602,272
By Geographic Area:
North America			1,009,524				611,630				565,408
Middle East			34,722				36,659				36,864
		$	1,044,246			$	648,289			$	602,272