The Social Network dropped only 30.9% at the North American box office this weekend, taking a chart-topping $15.5m and holding off competition from three new releases.

The film’s estimated second-weekend gross - taken from 2,771 theatres, for a per-theatre average of $5,594 - suggests that Sony’s Facebook drama has strong legs and may do better domestically than its $22.4m opening last weekend initially indicated. Its domestic total currently stands at $46.1m.

Warner’s Life As We Know It was the strongest of three lacklustre new wide releases. The romantic comedy, starring Katherine Heigl and Josh Duhamel as young singles forced to take care of a baby, took an estimated $14.6m (from 3,150 theatres, for a $4,646 average).

Co-produced with Village Roadshow and Gold Circle Films and directed by TV writer-producer Greg Berlanti (Brothers and Sisters) the film was cooly received by critics but lived up to most box office predictions.

Buena Vista’s Secretariat, the true story of the seventies racehorse and its owner, fell short of expectations with an estimated $12.6m weekend gross (from 3,072 theatres, for a $4,102 average).

Starring Diane Lane and John Malkovich and directed by Randall Wallace (Braveheart), the film was positioned as this year’s The Blind Side and marketed on several levels: as a sport film, a women’s film and an inspirational, faith-based story. It was mostly embraced by reviewers but its opening was well short of those for The Blind Side ($34.1m) and the more directly comparable Seabiscuit ($20.9m).

The third new wide release, Wes Craven’s 3D horror outing My Soul To Keep, was slammed by critics and managed only an estimated $6.9m (from 2,572 theatres, for a $2,690 average). Released by Universal for Relativity Media’s Rogue Pictures, the film stars Max Thieriot in the story of a serial killer who returns to his hometown to stalk children.

Among holdover titles, Warner’s Legend of the Guardians: The Owls of Ga’Hoole dropped only 35.6% in its third weekend to gross an estimated $7m, for a domestic total to date of $39.4m. And the same studio’s The Town was off just 34.9% in its fourth weekend, taking an estimated $6.4m for a total to date of $73.8m.

A number of films opened in limited release this weekend. Focus Features’ dramatic comedy It’s Kind of a Funny Story fell short of expectations with an estimated $2m from 742 theatres (average - $2,712). Overture’s dramatic thriller Stone took $73,000 from six theatres (average - $12,167). The Weinstein Company’s Nowhere Boy earned $56,000 from four theatres (average - $14,025). And Tamara Drew, from Sony Pictures Classics, grossed $19,300 from four theatres (average - $4,825)

Next weekend’s wide releases are: Paramount’s reality comedy sequel Jackass 3-D, with Johnny Knoxville and co performing wild stunts for director Jeff Tremaine; and Summit Entertainment’s graphic novel-based action comedy Red, with Bruce Willis, Karl Urban, Morgan Freeman, Mary-Louise Parker, John Malkovich and Helen Mirren starring for director Robert Schwentke.

Estimated Top 10 North America Oct 8-10, 2010

Film (Dist) / Est wkd gross / Est total to date

1 (1) The Social Network (Sony) SPRI $15.5m $46.1m

2 (-) Life As We Know It (Warner) WBPI $14.6m -

3 (-) Secretariat (Buena Vista) WDSMPI $12.6m -

4 (2) Legend Of The Guardians: The Owls of Ga’Hoole (Warner Bros) WBPI $7m $39.4m

5 (-) My Soul To Keep (Universal) Relativity $6.9

6 (4) The Town (Warner Bros) WBPI $6.4m $73.8m

7 (3) Wall Street: Money Never Sleeps (Fox) Fox Int’l $4.6m $43.7m

8 (5) Easy A (Screen Gems) SPRI $4.2m $48.1m

9 (7) Case 39 (Paramount) PPI/UIP/UPI $2.6m $9.6m

10 (6) You Again (Buena Vista) WDSMPI $2.5m $20.7m