SEO, paid search and social media: for obvious reasons, it’s difficult, if not downright impossible, for companies to thrive online without them.

Given their importance, one might expect that a growing number of companies would be eager to bring their SEO, PPC and social media activities in house, but according to SEMPO and Econsultancy’s State of Search Marketing Report 2011, just the opposite is happening.

The report is based on a survey which polled 900 client-side advertisers and agencies. It found that the number of companies handling SEO exclusively in-house fell from 51% in 2010 to 44% in 2011, and the number handling paid search in a similar fashion dropped from 47% to 38% over the same time period.

Even in the realm of social media, where companies are often encouraged to empower the voices within their companies, outsourcing is on the rise. In 2010, 62% of companies kept social media in-house. In twelve months, that has dropped to just 55%.

What gives? Why are companies increasingly looking for outside help with crucial online marketing activities?

For SEO and paid search, SEMPO and Econsultancy found a number of drivers: from a lack of in-house skills and time, to a lack of tools and technology.

Reasons for outsourcing paid search activity (company respondents):

Reasons for outsourcing paid search

Some advertisers and agencies, of course, also cited an economic benefit to outsourcing. For social media, time is the biggest factor, with 37% of respondents saying that social media is simply too time consuming to keep in-house exclusively.

That’s good news for specialists and focused agencies (eg. search and social media agencies), who in all three areas are preferred over more generalist providers, such shops that aim to be one-stop shops.

But is the growing amount of outsourcing good news for the companies choosing this route?

Obviously, outsourcing in and of itself isn’t bad. SEO, paid search and social media are only getting more sophisticated and competitive, and given that they basically constitute the digital marketing mix for many companies, the notion that they should be handed off, at least partially, to experts is easy to buy into.

And if this year’s State of Search Marketing Report is any indication, the trend of companies buying into this notion isn’t likely to reverse.

At the same time, companies need to exercise caution. To effectively manage outside vendors, and hold them accountable, investing in the development of some in-house resources is highly desirable. As we learned from J.C. Penney’s paid link nightmare, knowing what your vendors are up to is a must, and it’s hard to do that if you don’t understand what they’re doing.

That’s something the growing number of companies outsourcing their SEO, paid search and social media should keep in mind.