Pick how you're putting it in. Each way is from the maker's manual.
Base with LATCH
Where it can go: Rear-facing only. Never in a seat with a frontal airbag unless the airbag can be turned off; the back seat is the safest place. Only forward-facing vehicle seats; never on a rear-facing, side-facing or folded-down vehicle seat. No more than 4 inches (10 cm) of the base may hang past the edge of the vehicle seat. LATCH only at the standard 11-inch (28 cm) lower-anchor spacing; never use LATCH and the seat belt at the same time.
1Park on level ground and set the base on the chosen vehicle seat, making sure it does not block the seat-belt buckle.
2Lift the recline foot adjuster and raise or lower the base until the bubble sits between the arrows on the bubble level indicator.
3Pull up the LATCH release lever and let the LATCH straps out to full length, then take both connectors out of their storage compartments.
4Clip both LATCH connectors onto the vehicle's lower anchor bars.
5Press the base firmly into the vehicle seat while pulling up on the LATCH pull strap to tighten.
6Roll up the LATCH pull strap and tuck it into its storage slot.
Check it before you drive
Hold the base at each side and pull side to side and forward: it should not move more than 1 inch (25 mm).
The bubble must sit between the arrows on the base's bubble level indicator.
Check the installation before every use.
If the vehicle has inflatable seat belts, do not buckle the unused belt behind the seat when installing with LATCH.
Retold from Chicco manual (PDF). Your vehicle's manual also says which seats have LATCH anchors. When in doubt, a certified child passenger safety technician can check your install.
The carrier on and off the base
Clicking it onto the base
1Set the carrier into the installed base.
2Push down on the carrier so it locks onto the attachment hooks on the base.
The KeyFit 35 base: Stay-in-car base: LATCH (SuperCinch) or seat belt (LockSure), integrated anti-rebound bar; carrier also installs without base (European belt routing).
What Chicco says about its bases and carriers, for a second car or an older base.
KeyFit 30 carriers belong on KeyFit or KeyFit 30 bases. The KeyFit 35 and Fit2 carriers must not be used on a KeyFit or KeyFit 30 base. Chicco manual (PDF)
The KeyFit 35 base takes KeyFit, KeyFit 30 and KeyFit 35 carriers, but not the Fit2 carrier. Chicco manual (PDF)
Fit2 carriers only go on Fit2 bases, and KeyFit, KeyFit 30 or KeyFit 35 carriers must not be clicked into a Fit2 base. Chicco manual (PDF)
Chicco suggests one base for each car the baby rides in regularly, so the carrier can move between cars without reinstalling. Chicco help article
The newborn insert
What Chicco says about the insert
1Use only the Chicco newborn positioner that came with the seat, and only for babies 4 to 11 lb.
2Lay the positioner in the seat and pull the buckle through the slot in its bottom.
3Bring both harness straps over its side panels and push it firmly back into the seat.
4The separate head rest insert can be used with or without the positioner.
The maker warns: Never add other pillows or padding under or behind your baby.
Rear-facing only. Never in a seat with a frontal airbag unless the airbag can be turned off; the back seat is the safest place. Only forward-facing vehicle seats; never on a rear-facing, side-facing or folded-down vehicle seat. No more than 4 inches (10 cm) of the base may hang past the edge of the vehicle seat. LATCH only at the standard 11-inch (28 cm) lower-anchor spacing; never use LATCH and the seat belt at the same time.
How do I know the Chicco KeyFit 35 is installed right?+
Hold the base at each side and pull side to side and forward: it should not move more than 1 inch (25 mm). The bubble must sit between the arrows on the base's bubble level indicator. Check the installation before every use. If the vehicle has inflatable seat belts, do not buckle the unused belt behind the seat when installing with LATCH.
When do I use or remove the Chicco KeyFit 35 infant insert?+
Use only the Chicco newborn positioner that came with the seat, and only for babies 4 to 11 lb. Lay the positioner in the seat and pull the buckle through the slot in its bottom.
