tommygirl79 - yes, my post was meant to be harsh and possibly severe, but not in a meanhearted-way if you can understand that. Anyways, from your posts, this is what we know, or at least can figure...
1) you state that the 4-yr boy has been seen outside in his diaper/underwear the entire summer...since you don't mention anything about over the winter or early spring, this tells me either the family just moved in at the beginning of the summer or this has just started happening, but since you don't mention having known the kids from before, my assumption is that they just moved in a few months ago;
2) you state that you, and they, live down the street from an elementary school; we can then probably also assume that this isn't just happenstance so that the kids can have a safe place to play and that she/you wouldn't have the expense of driving them to school, ergo, she doesn't have alot of disposable income; also, being that close to a school means your street has a reduced speed limit, another consideration for letting your kids play outside;
3) you don't mention a father or ever meeting him; ergo, we're probably talking a single mom, or one just on the edge of becoming a single mom; this naturally leads to...
4) a tough women who really doesn't want neighbors poking into her business on a casual basis;
5) she didn't answer the door when the police arrived; from this we can reasonably assume that she's from a neighborhood, culture or background where authority figures were very rarely friendly, or that she doesn't trust since she would assume they would treat her as guilty until proven innocent (the basic DCFS scenario);
6) since you have never seen her outside with her children, she's either physically exhausted (either due to a medical condition or just because she's busy doing everything else around the house) or mentally exhausted during the day and unable to keep up with two young children, or she just doesn't care...however, no matter how hard of mother I've found, it is extremely rare that I've ever run across one that blatantly doesn't care about her children...ergo, she's probably exhausted during the day and collapses at night; and the fact that she's not outside only means she's not outside...I'm assuming her house has windows as well?
7) since it appears the children aren't out all night, she, or someone else is there to put them to bed and make sure they have a different set of clean clothes the next (even if it is just white underwear); if she is home at night, she undoubtedly collapses into bed, and if she has to work at night, you can guess when she sleeps;
8) starting to piece this together, she's more than likely living on alimony, welfare, or possibly both, and possibly minimun wage; in any case, if she is a single mother, even keeping house for two kids would be beyond my limits...I truly don't know how single parents do it even with one kid;
9) she's also probably embarressed or slightly ashamed (if we can use those terms these days) and purposefully avoids socialization, which means she either has her own support network from before or an extended family, or she's doing without any support network, however, individuals invariably have some network mechanism so we can assume they are at a distance and she really doesn't trust her new neighbors...can't blame her if after three months the new nieghbors call the police for child endangerment;
10) since you didn't mention the daughter wasn't not wearing clothes, I'm assuming she was; ergo, if one child has some clothes, we can almost trust that the boy has some clothes in his closet; now why he wasn't wearing any could be a no. of reasons but the two most likely are: a) his mom doesn't want him to wear clothes, which I think is hardly the case since the daughter is; or b) he doesn't like wearing clothes (very typical of a boy that age); the fact that he said he was cold, doesn't really negate (b).
11) and even though you asked the boy if he was cold, you failed to ask why he wasn't wearing any clothes which would have told you much; however, while low 60's might feel cold to you and could possibly as well for him, we swim in 60-degree weather up here...are you sure they're not from Alaska, Minnesota, or Canada?
12) surprisingly, numerous studies have shown that there is absolutely no correlation between sickness and outside temperature...it's an old wives tale...additionally, a normal active child will not get hypothermia from 60-degree weather; since he's obviously not outside at night when it's that cold, we're left with him being active outside during the day...question, is he sick all the time...sneezing, coughing, wheezing? Since you don't mention those indicators, he's probably healthier than a lot of us;
13) resultingly, the only real concern that's left is the highway that's close by; o.k., that could be scary...is there an embankment? Is it raised, or just have a guardrail between the next-door house and the highway? I know it's not completely the same but I grew up one house away from a major 4-lane thoroughfare that I remember even now that my mom put the fear of death in me as young as I can remember if I ever went close to that street...could his mother have done the same?
You also state you have children, which means more than one, and that you were picking them up from church after a mom's day out, which means they are too young to stay at home by themselves. O.k., here's your Christian challenge for you...why not invite her to your next mother's day out? Or, since children are the best evangelists, have your children ask her children to join them so their mom can have a little rest during the day.
Like I said, way too much to go into when not face-to-face, that's all I meant be it. For point of reference my BIL is a social worker and he will be the first to state that over half the cases on his desk should not be there as they are the result of trivial "concerns" being called in by neighbors who want to stay anonymous. I still think unless we went Chinese-style mass orphanages it's up to use to help our neighbors, not the federal government!
-R
Wait untill the child got ran over or abducted. Or maybe you should have waited untill mid December 
when it was snowing and the boy was out in his underwear to call the Police. I don't care how tired the mother is there is NO excuse for a child that young to be out all day in nothing but underwear without ADULT supervision (that does not mean his older sister). The problem with neighbor's today is not that they don't care about each other it's that neighbors like Lord Fantasia start to belittle, second guess and point fingers. When neighbors that care like Tommygirl79 do the right thing!!
