I have a fence which borders the property line of a neighbor. The ownership of the fence has recently come into question. I have lived at this property for 18 years and have always understood the fence to be on my property, in part because the 'ugly-side' faces inward, and the fact that I had a second fence of the same type and structure, on the opposite side of my property. This fence runs parralell to the border of the property, on the side of the adjoining house, but does not continue all the way to the street, thus allowing a person to walk from one property to the other without being impeded by the fence.
My neighboor has in recent years (since I have become a single parent) been mowing his lawn further and further onto my property....essentially passing the imagnary line which runs parralell to said fence. This year he has decided to 'repair' the fence. I am very concerned that his activities suggest he is trying to acquire more property by simply establishing ownership by working on the fence and maintaining the grass. How do I stop this?
It should be noted that I am a single mom of little means, and can't afford to have my property line determined by an engineer. However, I also feel that I should not have to pay money to establish my property line....just to prevent my neighboor from further encroachment. Since he is the one taking this agressive action, if necessary should he be the one to determine the line before he takes further action (such as taking the fence down, or placing a new fence up).
ANy advice conerning this is appreciated.

Adverse posession in MA
Have you tried talking to him? Maybe he just thinks he is helping you out and there is no dispute over the property line. In that case, you can simply thank him and tell him you will maintain the fence and the lawn in question.
If there is a dispute, you can follow this link for more information about adverse possession in Massachusetts. As you will see, there are several ways to deal with the issue. The most effective method is for you to send a certified letter (or hire an attorney to send a letter) asking him to stay off your land. If he refuses, you will then have to bring an action for trespass. Or, your could send him a certified letter giving him permission to work on your fence or to mow part of your lawn. That would undercut any claim he may make to ownership of the land through adverse possession. Also, if the land in question is registered land, he cannot make a claim to it through adverse possession. Good luck.