Third-quarter digital advertising revenue decreased 12.6 percent, while print advertising revenue decreased 46.5 percent. Digital advertising revenue was $47.8 million, or 60.3 percent of total Company advertising revenues, compared with $54.7 million, or 48.1 percent, in the third quarter of 2019. Digital advertising revenue decreased primarily as a result of lower creative services revenues. Print advertising revenue decreased as the COVID-19 pandemic further accelerated secular trends, largely impacting the luxury, entertainment, media and home furnishings categories.
Other revenues decreased 2.0 percent in the third quarter primarily as a result of fewer television episodes as well as lower revenues from commercial printing and live events. These declines were partially offset by higher revenues from licensing revenue related to Facebook News and affiliate referrals from Wirecutter.
Operating Costs
Total operating costs decreased 3.5 percent in the third quarter of 2020 to $387.3 million compared with $401.5 million in the third quarter of 2019, while adjusted operating costs decreased 3.7 percent to $370.4 million from $384.4 million in the third quarter of 2019 as a result of the factors discussed below.
Cost of revenue decreased 3.8 percent to $235.9 million compared with $245.1 million in the third quarter of 2019, largely due to lower print production and distribution and advertising servicing costs, which were partially offset by higher digital content delivery and journalism costs.
Sales and marketing costs decreased 21.2 percent to $50.6 million compared with $64.2 million in the third quarter of 2019, due primarily to lower media expenses, as well as lower advertising sales costs. Media expenses, a component of sales and marketing costs that represents the cost to promote our subscription business, decreased to $27.3 million in the third quarter of 2020 from $35.9 million in 2019. The Company expects media expenses to return to pre-pandemic levels in subsequent quarters.
Product development costs increased 27.9 percent to $34.1 million compared with $26.7 million in the third quarter of 2019, largely due to growth in the number of digital product development employees in connection with digital subscription strategic initiatives.
General and administrative costs increased 2.2 percent to $51.1 million compared with $50.0 million in the third quarter of 2019.
Other Data
Interest Income and Other, net
Interest income/(expense) and other, net increased in the third quarter of 2020 to $3.5 million income compared with an expense of $0.8 million in the third quarter of 2019 primarily as a result of the repurchase of the condo interest in our headquarters building in December 2019, which eliminated our outstanding debt.
Income Taxes
The Company had income tax expense of $7.3 million in the third quarter of 2020 compared with $6.1 million in the third quarter of 2019. The effective income tax rate was 17.8 percent in the third quarter of 2020 and 27.0 percent in the third quarter of 2019. The effective income tax rate for the third quarter of 2020 was lower than the statutory tax rate primarily due to a tax benefit from stock price appreciation on stock-based awards that settled in the quarter.
Liquidity
As of September 27, 2020, the Company had cash and marketable securities of $800.1 million, an increase from $683.9 million as of December 29, 2019.