This chapter introduces researchers to the concepts, measurement, and demographics related to asexuality and aromanticism. Asexuality is a sexual orientation that usually refers to people who experience little to no sexual attraction to people of any gender. Aromanticism is a romantic orientation, referring to those who experience little to no romantic attraction. This chapter explains the histories behind both concepts and discusses how their fluidity presents challenges for researchers. Best practices for including asexual and aromantic populations in survey research are also offered, followed by a discussion of demographic characteristics that have been observed through surveys of both populations. Overall, demographers are encouraged to consider how asexuality and aromanticism represent important, and often neglected, communities within the LGBTQIA+ umbrella.