[3] Goodrem began work on the album in 2006 and collaborated with several writers including Vince Pizzinga, Tommy Lee James, Jörgen Elofsson, Richard Marx, Stuart Crichton, and major contributions by Brian McFadden.

[9] The newspaper Sydney Morning Herald revealed that the album was going to be "a more upbeat, inspirational tone in her pop music.

"[10] In contrast to her previous album, which was darker because Goodrem had written about her cancer battle, Delta reflects changes in her personal life; her parents had divorced, she let her mother Lea stand down as her manager as well as discussed her relationship with pop-singer Brian McFadden, whom Delta co-wrote the majority of the songs on the album.

[11] To give a more mainstream appeal, Goodrem enlisted American songwriters and producers to work on the album, such as Tommy Lee James, John Shanks, Steve Kipner and Savan Kotecha, as well as British musicians Wayne Wilkins, Steve Mac and Wayne Hector, and Swedish record producers Carl Falk and Kristian Lundin.

"[13] Samantha Amjadali of The Herald Sun pointed out that Delta offers "a refreshing combination of topics and musical styles, and flits between power ballad, boppy pop and slow, sweet and sentimental.

"[14] Candice Keller of News.com.au noted that the album "welcomes the pop star to womanhood – a new beginning as a lady in love and wise from her time in the industry.

[14] The power pop "In This Life"[17] has a more guitar-driven vibe, which according to Cameron Adams of Herald Sun, "updates Goodrem's sound with the help of hit US producer John Shanks.

[19] According to Candice Keller of News.com.au, the song "prove[s] Goodrem can still embrace a sense of fun in her music, and can take a break from the seriousness of the tear-jerkers.

"[15] Keller also noted that "The Guardian" showcases that "Goodrem's signature power is evident,"[15] while hip-hop nuances are shown on "Barehands" and "Brave Face"[17] (an ode to keeping up appearances in public).

[14] The album also features the power ballads "Woman", a midtempo anthem[13] which was later recorded by American recording artist Toni Braxton for her seventh studio album Pulse (2010),[20] and "I Can't Break It to My Heart", which was also named a piano ballad.

Amjadali also praised Goodrem's talented as lyricist and skilled musician, writing that "it shines through in this, her most accomplished and enjoyable release yet," before calling the album "light and happy, sweet and summery.

"[14] Matthew Chisling of Allmusic gave the album 3.5 out of 5 stars, noting that Delta "came back more mature and classy than ever."

Chisling claimed that the album "is a mostly consistent sampling of a new, mature, smoothed out Goodrem, whose new vocal explorations with minor digital enhancements make her welcome by an even broader pop audience.

"[13] Chuck Taylor of Billboard named it "a vivacious 12-song showcase of versatility and melodic mastery", also noting that "timing is a bull's-eye for Goodrem's deliciously tasteful U.S.

"[16] Candice Keller of News.com.au wrote that Delta has "the Midas Touch", writing that the album "captures Goodrem as a sophisticated woman.

"[15] In his review for The Korea Times, Chung Ah-young remarked that in Delta, the singer "creates cohesive and haunting sounds from beginning to end through unique songs with her stunning songwriting and musical talent.

"[21] Chuck Campbell of Scripps News was very positive, writing that the self-titled project "sounds like the work of an old pro.

On 'Delta,' Goodrem packs the honest and uplifting qualities of her mentor, Olivia Newton-John, plus the stylized bombast of Celine Dion, the sense of adventure of Madonna, the introspection of Alanis Morissette and the vocal stunts of Mariah Carey.

[17] Brandy McDonnell of NewsOK was mixed, writing that Goodrem "boasts a lovely clear voice, but the uneven and slickly produced album, clearly designed to appeal to mainstream radio, doesn't do much to separate her from the Natasha Bedingfields and Colbie Caillats already crooning over the airways," but went on to praise the "'pop jewels' among all the sludge and rocks to make it worth the effort to sift through it.

[25] Goodrem held a Launch Party at the Sydney Opera House on Tuesday 9 October 2007, where 400 invitation-only guests attended.

She performed songs from the album, Including "Believe Again", "You Will Only Break My Heart", "Possessionless", "God Laughs" and "Angels in the Room".

Goodrem did an instore signing session at the Virgin Megastore at Times Square in New York City on 16 July 2008.

Goodrem was quoted as saying what viewers saw at the AFI Awards, regarding her remixed song and dance performance of Believe Again, in 2007, is only a taste of what is to be expected from her new tour.

In an article in Billboard magazine dated 12 July, Sony BMG Australia CEO Denis Handlin suggested that once Goodrem had finished promotional duties in the US for Delta, attention would be shifted to the UK and the rest of Europe.

[35] On its second week it sold 12,186 copies and was knocked off the top spot by The Eagles' album Long Road Out of Eden.