I had a harder time deciding on this question, simply because the information on it is so sparse.  In short, this question would permit a union (SEIU, the Service Employees International) to represent home-based child care providers in negotiating with the state.
I finally found some good arguments in the blogosphere, including Blue Mass Group and Left in Lowell. I was particularly swayed by a commenter on Left in Lowell.

The child-care providers aren’t employees.  They are small business owners.  They should have (and do have) a professional association.  That association can work with the state to guide regulation.  I don’t see how a union would be the right way for these businesses to negotiate with the state.  It would be one thing if these workers were asking to be represented by the SEIU.  I don’t see any evidence of that; I only see the SEIU aggressively trying to grow its membership.
The Yes on 3 group spins the question as one that is good for children.  Their filing statement with the state closes with “Vote yes for our children’s future.”  I can only draw another unflattering comparison to Helen Lovejoy.  I don’t see how unionization of these small business owners will improve child care.  I find it much easier to imagine higher costs with more regulation.

I do not believe that this law will improve the lives of children or the lives of home-based child care workers.  I’m voting No on 3 tomorrow.