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42666 LEGO Friends Pets Cat Birthday Party & Tree House thumbnail image

42666 LEGO Friends Pets Cat Birthday Party & Tree House
Images 6Description 
42666 LEGO Friends Pets Cat Birthday Party & Tree House
  • Cat Birthday Party & Tree House thumbnail
  • Cat Birthday Party & Tree House thumbnail
  • Cat Birthday Party & Tree House thumbnail
  • Cat Birthday Party & Tree House thumbnail
  • Cat Birthday Party & Tree House thumbnail
  • Cat Birthday Party & Tree House thumbnail

LEGO 42666 Cat Birthday Party & Tree House is a Friends set currently available at retail for $29.99 and is projected to retire in mid and late 2026. Current new-sealed secondary market prices range from $27 to $34, with the average below MSRP at $28.

Forecast Model

This represents the expected annual growth (CAGR) based solely on a forecast model.
LEGO 42666 Cat Birthday Party & Tree House is a Friends Pets set released in 2025, containing 321 pieces and 2 mini-dolls. The build centers on a cat-themed tree house and a rotating table with a birthday cake, accompanied by accessories such as a fish-shaped piñata, presents, banners, cat-shaped balloons, a cat toy, cat grass, a water fountain, and a litter box. It includes mini-dolls Leo and Paisley and five cat figures, with Churro as the birthday cat. The set launched in June 2025 in most regions, with a North American release in August 2025.

Once retired, the expected annual growth will be close to 2% after the second year, valuing the set between $32 and $32 shortly after it is retired.
Retirement risk.Cat Birthday Party & Tree House has been available for 12 months. Based on the average lifespan of other sets in this theme (11 months), this set may be at risk of retiring in the coming months.
All regions

For Sale (New/Sealed)

This chart shows the sales listing trends of 42666 Cat Birthday Party & Tree House.
 (US) Friends Cat Birthday Party & Tree House Building Toy - Pretend Play Buildin
BrickEconomy Choice
$22.99
(US) 42666 Friends Cat Birthday Party & Tree House Building-For Girls and Boy 6+ $23.74
-20.8%
(US) NEW Lego Friends 42666 Cat Birthday Party and Tree House $24.00
-20.0%
(US) Friends Cat Birthday Party 42666 321 Pieces Super Cute $24.38
-18.7%
(US) NEW 321 Pc Lego Friends 42666 Cat Birthday Party & Tree House Age 6+ Toy $24.98
-16.7%
(US) 42666 Friends Cat Birthday Party & Tree House NEW Factory Sealed 321pcs $24.99
-16.7%
(US) Friends Cat Birthday Party & Tree House 42666 NEW Factory Sealed $24.99
-16.7%
(US) 42666 Friends Cat Birthday Party & Tree House Building-For Girls and Boy 6+ $24.99
-16.7%
(US) Friends Cat Birthday Party & Tree House 42666 NEW Factory Sealed $26.95
-10.1%
(US) Friends Cat Birthday Party & Tree House Building Toy 42666 Pretend Play $26.99
-10.0%
(US) Friends Cat Birthday Party & Tree House 42666 NEW Factory Sealed $27.48
-8.4%
(US) 42666 LEGO Friends Pets Cat Birthday Party & Tree House (Ships for FREE) $27.95
-6.8%
(US) Friends Cat Birthday Party & Tree House 42666 (New Sealed) FREE SHIPPING. $27.99
-6.7%
(US) Friends Cat Birthday Party & Tree House Building Toys 42666 For Kids Age 6+ $28.30
-5.6%
(US) Friends Cat Birthday Party & Tree House 42666 Building Toy NEW Sealed $29.94
-0.2%
(US) Friends Cat Birthday Party & Tree House (42666) - 2025 NEW/SEALED $29.99
(US) Friends Cat Birthday Party & Tree House Set (42666) $29.99
(US) Friends Cat Birthday Party Tree House Building 42666 - NEW Age 6+ $29.99
(US) Friends Cat Birthday Party & Tree House Set 42666 321pcs New Sealed Toy $29.99
(US) 42666 Friends Cat Birthday Party & Tree House Building-For Girls and Boy 6+ $29.99
(US) Official LEGO Cat Birthday Party & Tree House $29.99
Show 16 more listings

Mini-doll figures

Cat Birthday Party & Tree House contains 2 mini-doll figures. The mini-doll figure is exclusive to this set.
frnd846
Leo
Leo from Friends wearing a coral and magenta checkered sleeveless shirt, yellow cropped trousers, and medium azure shoes - frnd846
Exclusive
Value $3.36
frnd819
Friends Paisley
Paisley mini-doll in a bright light yellow and medium lavender tank top, medium lavender shorts, and dark tan shoes - frnd819
2 sets
Value $3.66

Sets in Friends / Pets

42651 Horse and Pet Vet Clinic

Theme / Subtheme Friends / Pets
Year 2025
Pieces / Mini-doll figures 428 / 3
Availability Retired
42651 LEGO Friends Horse and Pet Vet Clinic
Retail $49.99
Value ~$49.99

42615 Pet Adoption Day

Theme / Subtheme Friends / Pets
Year 2024
Pieces / Mini-doll figures 400 / 3
Availability Retired
42615 LEGO Friends Pet Adoption Day
Retail $44.99
Value $40.00

42678 Pet Accessories Van

Theme / Subtheme Friends / Pets
Year 2026
Pieces / Mini-doll figures 237 / 2
Availability Retail
42678 LEGO Friends Pet Accessories Van
Retail $19.99
Available at retail

41698 Pet Playground

Theme / Subtheme Friends / Pets
Year 2022
Pieces / Mini-doll figures 210 / 2
Availability Retired
41698 LEGO Friends Pet Playground
Retail $19.99
Value $24.15
Growth  +20.8%
Annual growth 5.6%

3942 Heartlake Dog Show

Theme / Subtheme Friends / Pets
Year 2012
Pieces / Mini-doll figures 183 / 1
Availability Retired
3942 LEGO Friends Pets Heartlake Dog Show
Retail $19.99
Value $25.62
Growth  +28.2%
Annual growth 3.3%

42601 Hamster Playground

Theme / Subtheme Friends / Pets
Year 2024
Pieces / Mini-doll figures 167 / 2
Availability Retired
42601 LEGO Friends Pets Hamster Playground
Retail $19.99
Value $29.99
Growth  +50.0%
Annual growth 11.8%

42679 Heartlake City Bunny Hotel

Theme / Subtheme Friends / Pets
Year 2026
Pieces / Mini-doll figures 161 / 2
Availability Retail
42679 LEGO Friends Pets Heartlake City Bunny Hotel
Retail $19.99
Available at retail

41001 Mia's Magic Tricks

Theme / Subtheme Friends / Pets
Year 2013
Pieces / Mini-doll figures 90 / 1
Availability Retired
41001 LEGO Friends Pets Mia's Magic Tricks
Retail $9.99
Value $12.22
Growth  +22.3%
Annual growth 3.1%

42612 Cat Playground Adventure

Theme / Subtheme Friends / Pets
Year 2024
Pieces / Mini-doll figures 87 / 2
Availability Retired
42612 LEGO Friends Pets Cat Playground Adventure
Retail $10.99
Value $11.74
Growth  +6.8%
Annual growth 4.2%

42640 Guinea Pig Playground

Theme / Subtheme Friends / Pets
Year 2025
Pieces / Mini-doll figures 86 / 2
Availability Retired
42640 LEGO Friends Pets Guinea Pig Playground
Retail $9.99
Value $15.00
Growth  +50.2%

41383 Olivia's Hamster Playground

Theme / Subtheme Friends / Pets
Year 2019
Pieces / Mini-doll figures 81 / 1
Availability Retired
41383 LEGO Friends Pets Olivia's Hamster Playground
Retail $9.99
Value $14.60
Growth  +46.1%
Annual growth 4.3%

41029 Stephanie's New Born Lamb

Theme / Subtheme Friends / Pets
Year 2014
Pieces / Mini-doll figures 78 / 1
Availability Retired
41029 LEGO Friends Pets Stephanie's New Born Lamb
Retail $9.99
Value $12.75
Growth  +27.6%
Annual growth 2.0%

3935 Stephanie's Pet Patrol

Theme / Subtheme Friends / Pets
Year 2012
Pieces / Mini-doll figures 73 / 1
Availability Retired
3935 LEGO Friends Stephanie's Pet Patrol
Retail $9.99
Value $15.76
Growth  +57.8%
Annual growth 5.7%

42665 Puppy Playground

Theme / Subtheme Friends / Pets
Year 2025
Pieces / Mini-doll figures 66 / 2
Availability Retail
42665 LEGO Friends Pets Puppy Playground
Retail $9.99
Available at retail

3938 Andrea's Bunny House

Theme / Subtheme Friends / Pets
Year 2012
Pieces / Mini-doll figures 62 / 1
Availability Retired
3938 LEGO Friends Pets Andrea's Bunny House
Retail $9.99
Value $17.44
Growth  +74.6%
Annual growth 3.2%

42635 Dog Grooming Car

Theme / Subtheme Friends / Pets
Year 2024
Pieces / Mini-doll figures 60 / 2
Availability Retired
42635 LEGO Friends Pets Dog Grooming Car
Retail $9.99
Value $14.27
Growth  +42.8%

41396 Puppy Playground

Theme / Subtheme Friends / Pets
Year 2020
Pieces / Mini-doll figures 57 / 1
Availability Retired
41396 LEGO Friends Pets Puppy Playground
Retail $9.99
Value $12.78
Growth  +27.9%
Annual growth 2.9%

30697 Nova's Doghouse Build

Theme / Subtheme Friends / Pets
Year 2025
Pieces / Mini-doll figures 50 / 1
Availability Retail
30697 LEGO Friends Pets Nova's Doghouse Build
Retail $4.99
Available at retail

My Collection

Cat Birthday Party & Tree House Reviews

12 reviews
4.8
Collectors
Investors
BrickEconomy Member Review
“The LEGO Friends Cat Birthday Party & Tree House set stands out for its cat-themed design, colorful pieces, and interactive features like a rotating table and fish-shaped piñata. Easy-to-follow instructions and detailed accessories, including five cat figures and themed party items, make it a strong choice for younger builders.”
 

About Friends Pets

The LEGO Friends Pets subtheme focuses on everyday pet care, adoption, and animal playtime in Heartlake City, spanning from 2012's 3935 Stephanie's Pet Patrol and 3942 Heartlake Dog Show through long-running releases like 41698 Pet Playground, 42615 Pet Adoption Day, and 42666 Cat Birthday Party & Tree House. The line covers hamsters, guinea pigs, cats, dogs, and bunnies with playsets such as 42612 Cat Playground Adventure, 42635 Dog Grooming Car, 42640 Guinea Pig Playground, and 42651 Horse and Pet Vet Clinic. Recent 2026 releases include 42678 Pet Accessories Van and 42679 Heartlake City Bunny Hotel.

Pets was introduced in 2012 and currently consists of 19 sets.
Read more
Discover a paw-some building kit for girls, boys and cat-lovers aged 6 and up. The LEGO Friends Cat Birthday Party & Tree House (42666) toy comes with 2 minidolls, 5 cat figures and lots of accessories for imaginative play packed with sweet kitty moments.

This fun toy sets the scene for Churros birthday party. 4 of Churros feline friends are here too, plus LEGO Friends characters Leo and Paisley. Explore the fun details, including birthday presents, banners and cat-shaped balloons. Kids will love guiding the pets around the cat tree house, where theres a fish-shaped piata, a cat toy, cat grass, a water fountain and litter box. Then its time for the cats to sit at the rotating table to enjoy Churros birthday cake. With so many ways to play with this animal playset, kids can tell a different friendship story every time.

Discover more exciting creative toys (sold separately) in the LEGO Friends universe. This LEGO set comes with the LEGO Builder app for intuitive building.

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