Read pp 66-70 in your text and the main NYS accomplice liability statute below. The reading in the text is confusing on this topic since it spends a lot of time distinguishing between accessories and accomplices. For our purposes they are basically the same. The NYS PL refers to the concept as Accessorial Conduct which other jurisdictions call Accomplice Liability or "Parties to a crime"

20.00 Criminal liability for conduct of another.

When one person engages in conduct which constitutes an offense,

another person is criminally liable for such conduct when, acting with

the mental culpability (MR) required for the commission thereof, he solicits,

requests, commands, importunes, or intentionally aids such person to

engage in such conduct.

The key language in the above statute is underlined. Both the principal and the accomplice(s) must have a shared MR. In other words, the Prosecution has to show that all parties are on the same page of the playbook. If they aid each other in committing the offense they are equally culpable whether they are the principle or the accomplice.

Ex:

A & B plan to burglarize C's house. A goes into the house and takes property. B acts as a lookout. A & B are both guilty of Burglary