Marcia Donnelly is the Assistant Principal of Edward J. Tilghman Middle School. She is an efficient disciplinarian whom the students have learned to obey. A veteran administrator, Mrs. Donnelly has become used to the chaotic environment of the school, but she still feels frustrated with the difficulty of keeping order among the children and retaining teachers from year to year. Donnelly is world-weary to the point where she sees an in-school stabbing victim being HIV-negative as a silver lining. She performs sweeps of the school grounds looking for concealed weapons on a regular basis.
Donnelly employs Dennis "Cutty" Wise — ostensibly as a custodian — to perform the duties of a truant officer. By forcing truants to attend one day in September and another in October, the school secures more funding. Cutty eventually returns to her to resign the post because he expected to be doing something more rewarding. She works with Howard "Bunny" Colvin in setting up an initiative to separate students into two groups to improve discipline. She urges Colvin to protect Principal Withers from the consequences of dividing the students, because he has gone out on a limb to support the initiative. She selects the students for the program with input from her colleague Grace Sampson.
Donnelly meets with Bubbles and allows his young assistant Sherrod to enroll in the school. She insists that Sherrod is socially promoted to the eighth grade because of his age. She tells Bubbles that he cannot be allowed to return to the last grade he attended because of the difficulties it would present regarding classroom discipline and funding. She is supportive of impoverished student Duquan "Dukie" Weems and sends clothes home for him via his classmate Crystal Judkins.
Donnelly convinces eighth grade student Randy Wagstaff to become an informant against other students by threatening to call his foster mother when he is caught with a fake hall pass. When Randy is later involved as a lookout in a possible rape on school grounds Donnelly is forced to suspend him. He tells her that he knows about a murder to try and convince her not to call his foster mother and Donnelly is forced to hand him over to the police department.
Donnelly has a relationship based on mutual respect with the Principal, Claudell Withers. He allows her to handle the operational aspects of running the school while he deals more with external interests like the education board and the parents. Donnelly tries to protect the school from being taken over by the state by focusing on improving performance in state assessments. She insists on her teachers sticking to core subjects and is against deviations from the curriculum. She tries to guide trainee teacher Roland "Prez" Pryzbylewski into following this strategy.
On episode -30-, Duquan visits to go see Mr. Pryzbylewski to see if he can borrow money off him like 500$, so Maricia comes down, she tells him he cant go in the school premises because he is not a student anymore and so she get Roland Pryzbyleski.
Michael Lee - Namond Brice - Randy Wagstaff - Dukie Weems - Donut - Marcia Donnelly - Claudell Withers - Darnell Tyson - David Parenti - Zenobia Dawson - Crystal Judkins - Albert Stokes - Karim Williams - Grace Sampson