There are a number of themes at work in Seamus Heaney's sadly autobiographical "Mid-term Break." Like the narrator of the poem, Seamus Heaney lost his brother in a car accident when the child was only four years old. Because of this, the thematic concepts of death and loss are prevalent in the poem and are used to color even the potentially joyful moments that Heaney provides as he moves toward his themes.

One theme that is present in the work is that death diminishes potential happiness. This emerges after the reader understands the poem but is hinted at in the first stanza:

I sat all morning in the college sick bay
Counting bells knelling classes to a close.
At two o'clock our neighbours drove me home. (1–3)

The poem begins with what seems to be a fairly common occurrence. The midterm break is coming up, and someone is in a sick bay. One many think that perhaps the narrator is trying to skip out on the last day of classes. However, the language used in line two shifts the reader away from any happy expectations through the description of the "knelling" of the counting bells. Normally, the bells that signal the ends of classes would be a welcome sound, particular on the day before a break. Here, though, the use of "knelling" suggests something foreboding, as a death knell.

As the poem continues, the feeling of dread expands as Heaney presents the reader with more moments where happy occurrences have been tainted. The narrator is headed home, which should be a happy event. He meets his father on the porch, and his father is crying, but not out of happiness at the reunion, as he may have had a tragedy not occurred shortly before. Instead the father is crying for the family's loss: one of the youngest children, a four-year-old younger brother, has been hit by a car and killed. The sadness of the reunion continues as the narrator sits and holds his mother's hand as she "coughed out angry tearless sighs" (13). Again, under different circumstances, this contact may have consisted of happy, tearless signs of relief and reunion, but the tragedy has taken away that possibility.

Finally, the narrator's reunion with the four-year-old brother is also filled with sadness. The narrator hasn't seen his younger brother in a month and a half, but instead of surprising the child by waking him from sleep upon the narrator's return, the narrator can only sit beside his younger brother as the child is lying in wake:

Next morning I went up into the room. Snowdrops
And candles soothed the bedside; I saw him
For the first time in six weeks. Paler now,
Wearing a poppy bruise on his left temple,
He lay in the four-foot box as in his cot.
No gaudy scars, the bumper knocked him clear.
A four-foot box, a foot for every year. (16–22)

Throughout the poem, a number of reunions have been diminished due to the tragic death of a child. For most people, a break from schooling is a welcome change, a chance to rest, and an opportunity to catch up with family. For the narrator of "Mid-Term Break," the break instead represents a fracturing of family and a reunion that will never occur.