Generally speaking, yes, you will capitalize book titles using headline capitalization, i.e. all major words of the title are capitalized. The first word of the title will be capitalized, as well, even if it's a "minor" word like "the" or "a." (In Chicago style, prepositions like "in" or "across" are not capitalized.)
Examples:
- A Tale of Two Cities
- The Possibility of Life: Science, Imagination, and Our Quest for Kinship in the Cosmos
- A Night in the Lonesome October
This is true for your MLA and Chicago style citations and narrative mentions of books.
Exception in APA citations:
Source titles in APA citations are always written like sentences: the first word and proper nouns capitalized, the rest are lower case. However, if you refer to a book in the text of your paper, regular capitalization rules will apply.
Example:
In an essay: In the book The Possibility of Life, science fiction imaginings of extraterrestrial life are juxtaposed against the development of our scientific understanding of our place in the universe (Green, 2023).
On the references page: Green, J. (2023). The possibility of life: Science, imagination, and our quest for kinship in the cosmos. Hanover Square Press.
