Condensed Consolidated Statements of Income (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Jul. 03, 2011	Jun. 27, 2010	Jul. 03, 2011	Jun. 27, 2010
Revenue	$ 673,792	$ 562,365	$ 1,897,482	$ 1,573,850
Subcontractor costs	(193,288)	(192,237)	(581,093)	(534,295)
Other costs of revenue	(398,131)	(297,730)	(1,083,503)	(833,869)
Selling, general and administrative expenses	(42,965)	(39,692)	(129,897)	(118,337)
Operating income	39,408	32,706	102,989	87,349
Interest expense - net	(1,703)	(336)	(4,478)	(943)
Income before income tax expense	37,705	32,370	98,511	86,406
Income tax expense	(12,957)	(11,731)	(32,928)	(32,728)
Net income including noncontrolling interests	24,748	20,639	65,583	53,678
Net income attributable to noncontrolling interests	(909)		(1,944)
Net income attributable to Tetra Tech	$ 23,839	$ 20,639	$ 63,639	$ 53,678
Earnings per share attributable to Tetra Tech:
Basic (in dollars per share)	$ 0.38	$ 0.34	$ 1.03	$ 0.87
Diluted (in dollars per share)	$ 0.38	$ 0.33	$ 1.01	$ 0.86
Weighted-average common shares outstanding:
Basic (in shares)	62,203	61,560	61,967	61,380
Diluted (in shares)	62,934	62,181	62,745	62,115