"The natural environment around me is a huge inspiration. I try to design in harmony with that. We take the environment into account and are developing this area on a daily basis throughout the company. Not killing fellow creatures helps."
In 2004, she designed clothes for Madonna's Re-Invention Tour, Annie Lennox's summer tour, and Gwyneth Paltrow's and Jude Law's costumes for the film Sky Captain and the World of Tomorrow.
She also launched a joint-venture line with Adidas, establishing a long-term partnership with the corporation in September 2004. This line is a sports performance collection for women. The collection includes apparel for swim, gym, running, tennis and wintersports, as well as bags. McCartney's favorite pieces in the collection come with a special reflector keychain. In early 2006, the keychain was in the shape of a pink heart and in later 2006, it was in the shape of a gray wolf's head. In January 2007, Stella McCartney announced that she would be adding a branch called Gym Yoga to her sports range for Adidas. Gym Yoga spring/summer 2007 collection is inspired by ballet and dance uniforms. The collection features double-layered tank tops with deep necklines, low-waisted skinny trousers and lightweight rubber shoes. Her Adidas contract was extended until 2010.
In 2005, she designed a range of clothing and accessories for H&M to boost public awareness of her own brand and to create more affordable options for her fans. The line was released in November of that year and sold out almost immediately on launch day, due to the similarity (in many cases, almost direct copies) between her expensive main line and the H&M line. On 12 March 2007, McCartney's limited edition 42-piece range was released to just 100 Target stores exclusively in Australia. The range was priced from $30 for a silk scarf to $200 for a taffeta trench coat. The collection was made in China. Scenes of near hysteria broke out as women stormed the stores to buy the collection. A problem was "clothing scalpers", who bought up large amounts of the range to resell on eBay at a high mark-up. Later, a large number of buyers returned their Stella clothes to Target complaining of strange, non-standard sizing that was bigger than the norm. A Target spokesperson defended the range saying that Stella's look was "generous" and "oversized". Later, returned Stella clothes languished on the racks having had their prices slashed by up to 60 percent.
In January 2008, McCartney's collaboration with lingerie label Bendon was scheduled to be released to department stores, speciality stores and Stella McCartney stores. McCartney was also scheduled, in early 2008, to release a line of handbags for LeSportsac. The collection will have 30 to 40 styles and will range from $200–$500. The collection will consist of travel bags, luggage, baby accessories and bags for mothers with infants and toddlers. The line is to be sold at high end retailers, the Los Angeles and New York Stella McCartney stores, select LeSportsac boutiques, and will be available for purchase online.
In 2009, Stella announced a children's wear collaboration with retailer Gap. Expected to launch in November this year, the collection will be carried in selected GapKids and babyGap stores in the United States and Canada, the UK, France, Ireland and Japan.
Since starting her own label McCartney has also collaborated on projects with several artists including Reem Alasadi, Gary Hume, R. Crumb, Jeff Koons, David Remfry and Ed Ruscha.