I'm trying to find the best way to buy LEGOs for my growing family. 
But, I don't want to buy Lego's that don't fit together.  There must
be a pathway to buy legos such that all the sets can be used together.
 I imaging an index where Type A works with Type C which works with
Type C.  Something like that.  I would think that the size of the lego
must be indexed somewhere.

Specifically, I want to be able to have my kids incorporate their
large toddler lego with those that I'll buy them later in life.  There
must be a way to move from the large sets of legos for young toddlers
up to the smaller sets for older kids.  I imagine that their are
adaptor sets, like the missing link.

So my questions are:
a) What is the lego indexing system where I can see what lego sets go with what
b) is their a clear pathway to buying legos that fit together as a child grows
c) and additional information about how best to purchase legos is appreciated

Howdy georgemonical-ga,

First, there are the LEGO preschool sets, outlined here.
http://www.lego.com/eng/preschool/productsList.asp

"BABY"
http://www.lego.com/eng/preschool/baby.asp

"... LEGO BABY playsets are specially designed for infants aged 6 to
18 months."

"QUATRO"
http://www.lego.com/eng/preschool/quatro.asp

"Designed for children aged 1 to 3 years, QUATRO products are made of
softer plastic and are just the right size for small hands."

"DUPLO"
http://www.lego.com/eng/preschool/duplo.asp

"The classic building system for children aged 2 to 6 years has returned
with all of the creative play that kids and parents have loved for years."

Then there is everything else, the "regular" LEGO bricks, which come in
various "themes," such "Technics" and "Belville."
http://www.lego.com/eng/products/

"Technic"
http://www.lego.com/eng/create/technic/

"Belville"
http://www.lego.com/belville/

The LEGO web site addresses the compatibility issue.

"Are DUPLO and LEGO BABY bricks compatible with LEGO SYSTEM bricks?"
http://www.lego.com/eng/service/faqs.asp?section=ConsumerService-FAQ-Products&catid=2564F39D-C742-4F3A-ABCC-F6C8A22600E3&faqid=1660

"In general all LEGO bricks can be combined in many variations. However,
there are some limitations when using the larger LEGO DUPLO bricks with
normal LEGO bricks. For example, LEGO DUPLO bricks may only be securely
fitted onto larger LEGO bricks. If you want to combine the very large
LEGO BABY with LEGO DUPLO bricks please use adapter bricks. These
special bricks (set no. 5022) can be ordered from LEGO Direct (subject
to availability)."

"Are Belville elements compatible with regular LEGO bricks?
http://www.lego.com/eng/service/faqs.asp?section=ConsumerService-FAQ-Products&catid=3DD29552-3A84-4C36-8506-5A8DA9EEC48C&faqid=1460

"Yes, the elements found in Belville sets will snap together with LEGO
bricks. However, the figures found in Belville sets are larger than
traditional LEGO mini figures."

"Are TECHNIC sets compatible with LEGO sets?
http://www.lego.com/eng/service/faqs.asp?section=ConsumerService-FAQ-Products&catid=2BCCCC7B-FD01-4AAE-AD0F-35244A7898DC&faqid=1596

LEGO TECHNIC sets contain elements that have the same interlocking system
as the LEGO bricks and can therefore be used together, depending on the
function of the element."

The #5022 adapter bricks are not currently available at LEGO Direct.
http://shop.lego.com/

They have a page with contact information, in case you want to find out
when they might have #5022 adapter bricks.
http://www.lego.com/eng/service/contactus.asp

LEGO Shop at Home
P.O. Box 1310
Enfield, CT 06083-1310
Tel. +1 800 453 4652
Fax: +1 888 Fax LEGO

You could sign up your children to a free subscription to LEGO magazine.
http://club.lego.com/eng/magazine/subscription.asp

They have set specials, catalogs, and coupons on occasion.  The magazine
gives building tips as well.

All of the above said, you will find that as a child gets older, the less
they will play with the "younger" sets.  They will outgrow their early sets
of LEGO bricks just like they outgrow everything else.

Because of this, you might want to buy the younger children just one bucket
of these early sets, and see if they take to LEGO bricks.  Even when they
get older, they might just not like LEGO bricks.

As for a buying strategy, you will get the "biggest bang for your buck" by
buying "bucket" sets, that is, buckets of LEGO bricks, such as this Small
QUATRO Bucket from Buy.com.
http://www.buy.com/retail/product.asp?sku=201093357

Here are more bucket sets from the LEGO web site.
http://shop.lego.com/leaf.asp?cn=44&d=34&t=10

Toys"R"Us has specials on various LEGO sets at times, as do other toy stores.
You can find your nearest Toys"R"Us store here.
http://www6.toysrus.com/store/

KB Toys is another good source.
http://www.kbtoys.com/

Google has their Froogle service that can come in handy.
http://froogle.google.com/froogle?q=LEGO

I like the buckets not only for their price, but they also tend to stimulate
the imagination a bit more than the sets which seem to lead the child to make
"just" the car, etc. the set is designed around.

If you need any clarification, please feel free to ask.


Search strategy:

I went through a phase of collecting LEGO bricks.

Searched the LEGO web site to check out their current sets.
http://www.lego.com

Looking Forward, denco-ga - Google Answers Researcher

---

Clarification of Answer by denco-ga on 28 Mar 2005 21:27 PST

Apologies, but the link to the LEGO web site should have been formatted:

http://www.lego.com/