Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 28, 2020	Jun. 30, 2019	Jun. 28, 2020	Jun. 30, 2019
Revenue	$ 709,771	$ 825,793	$ 2,241,527	$ 2,265,846
Gross profit	114,397	117,987	321,134	313,141
Selling, general and administrative expenses	(50,822)	(53,146)	(148,299)	(145,016)
Contingent consideration – fair value adjustments	(50)	0	1,521	(28)
Income from operations	63,525	64,841	174,356	168,097
Interest expense	(3,564)	(3,546)	(10,412)	(9,607)
Income before income tax expense	59,961	61,295	163,944	158,490
Income tax expense	(14,458)	(12,044)	(34,710)	(11,263)
Net income	45,503	49,251	129,234	147,227
Net income attributable to noncontrolling interests	(6)	(18)	(29)	(86)
Net income attributable to Tetra Tech	$ 45,497	$ 49,233	$ 129,205	$ 147,141
Earnings per share attributable to Tetra Tech:
Basic (in dollars per share)	$ 0.84	$ 0.90	$ 2.38	$ 2.67
Diluted (in dollars per share)	$ 0.83	$ 0.88	$ 2.34	$ 2.63
Weighted-average common shares outstanding:
Basic (in shares)	53,985	54,819	54,366	55,101
Diluted (in shares)	54,692	55,768	55,161	56,034
Subcontractor costs
Cost of revenue	$ (149,494)	$ (202,597)	$ (482,768)	$ (503,902)
Other costs of revenue
Cost of revenue	$ (445,880)	$ (505,209)	$ (1,437,625)	$ (1,448,803)