At the start of a sentence
Use a capital letter to indicate the start of a new sentence.
Likewise, capitalize the first letter of any quotation appearing in running text that is a complete sentence itself; otherwise, leave it in lowercase. Compare:
According to Phillips, “Teachers everywhere are eager for clearer, more compelling standards that take the mystery out of what they're supposed to be teaching.”
Schank writes that while learning objectives may “seem like a good idea for the basis of curriculum design,” they are actually “one of the main evils in the school system.”
Exceptionally, use a lowercase letter at the start of sentences, titles and headlines that begin with a brand name or other proper noun conventionally written with a lower-case first letter. Examples:
eLearnCenter Research Paper Series
iPhone, therefore I am
Finally, unlike in Catalan, in English the first-person singular pronoun I is always capitalized. Example:
Professor Guasch and I are pleased to welcome you all to the conference.