Bosselaar's poems are written in straightforward English. Her lines vary from long to short and her sentence structures can be simple or complex. Her vivid images add to the poem's meaning on both an obvious and symbolic level. For example, her poem "Against Again" explores the story of a child left in a convent by her disinterested mother. Bosselaar writes that as an infant the child:
cranes to see her mother's
face, but the stroller's
black hood is in the way.
In these lines, the "black hood" not only creates a vivid picture but hints at the black outfits of the uncaring nuns who later replace her mother.
Bosselaar's work deals with people and relationships, particularly the inability of people to connect with one another. Perhaps because she lives in New York City, she often writes about strangers. Family is also a central element in her work. A consistent theme is the idea of longing for other people: an absent mother in "Against Again," a lost daughter in "Stillbirth." Even married couples in her work often cannot relate well to one another. A sense of isolation and loneliness pervades many of the poems.
Bosselaar was raised in Belgium and is multilingual. She often writes about the inability of words to express the depth of human feeling. For example, in her poem, "The River's Mouth, The Boat, The Undertow," she writes about a supposedly untranslatable Czech word for sorrow:
...we have no word for this in English. But here's the point --
What if we did? Would a word make such pain more tolerable?
As if language could help.
At other times, she has written about the power of language to establish at least a degree of human connection, for instance in her poem, "Friends."
Bosselaar is a master of form. Although her poems generally do not rhyme, she writes in a wide range of complex forms including the sonnet sequence and sestina. As with any good poet, her use of form reflects the meaning of the poem. For example, her poem "Stillbirth" is a pantoum, a form that involves repeating whole lines at particular points in the poem. In the poem, the repetition of these lines reflects the narrator's recurrent thoughts of grief over her lost daughter. Bosselaar's line breaks and the placement of the lines on the page are also always carefully orchestrated to add to the poem's meaning.