In social contexts, autistic people may respond and behave differently than individuals without ASD.

Impairments in social skills present many challenges for autistic individuals. Deficits in social skills may lead to problems with friendships, romantic relationships, daily living, and vocational success. One study that examined the outcomes of autistic adults found that, compared to the general population, autistic people were less likely to be married, but it is unclear whether this outcome was due to deficits in social skills or intellectual impairment, or some other reason. A factor to this is likely discrimination against autistic people which is perpetuated by myths; for example: the myth that autistic people have no empathy.

Prior to 2013, deficits in social function and communication were considered two separate symptom domains of autism. The current social communication domain criteria for autism diagnosis require individuals to have deficits across three social skills: social-emotional reciprocity, nonverbal communication, and developing and sustaining relationships.

A range of social-emotional reciprocity difficulties (an individual's ability to naturally engage in social interactions) may be present. Autistic individuals may lack mutual sharing of interests, for example many autistic children prefer not to play or interact with others. They may lack awareness or understanding of other people's thoughts or feelings – a child may get too close to peers (entering their personal space) without noticing that this makes them uncomfortable. They may also engage in atypical behaviors to gain attention, for example a child may push a peer to gain attention before starting a conversation.

Older autistic children and adults perform worse on tests of face and emotion recognition than non-autistic individuals, although this may be due to the prevalence of alexithymia in autistic people rather than autism itself.

Autistic people experience deficits in their ability to develop, maintain, and understand relationships, as well as difficulties adjusting behavior to fit social contexts. ASD presents with impairments in pragmatic communication skills, such as difficulty initiating a conversation or failure to consider the interests of the listener to sustain a conversation. The ability to be focused exclusively on one topic in communication is known as monotropism, and can be compared to "tunnel vision". It is common for autistic individuals to communicate strong interest in a specific topic, speaking in lesson-like monologues about their passion instead of enabling reciprocal communication with whomever they are speaking to. What may look like self-involvement or indifference toward others stems from a struggle to recognize or remember that other people have their own personalities, perspectives, and interests.] Another difference in pragmatic communication skills is that autistic people may not recognize the need to control the volume of their voice in different social settings – for example, they may speak loudly in libraries or movie theaters.

Autistic people display atypical nonverbal behaviors or have difficulties with nonverbal communication. They may make infrequent eye contact – an autistic individual may not make eye contact when called by name, or they may avoid making eye contact with an observer. Aversion of gaze can also be seen in anxiety disorders, however poor eye contact in autistic children is not due to shyness or anxiety; rather, it is overall diminished in quantity. Autistic individuals may struggle with both production and understanding of facial expressions. They often do not know how to recognize emotions from others' facial expressions, or they may not respond with the appropriate facial expressions. They may have trouble recognizing subtle expressions of emotion and identifying what various emotions mean for the conversation. A defining feature is that autistic people have social impairments and often lack the intuition about others that many people take for granted. Temple Grandin, an autistic woman involved in autism activism, described her inability to understand the social communication of neurotypicals, or people with typical neural development, as leaving her feeling "like an anthropologist on Mars". They may also not pick up on body language or social cues such as eye contact and facial expressions if they provide more information than the person can process at that time. They struggle with understanding the context and subtext of conversational or printed situations, and have trouble forming resulting conclusions about the content. This also results in a lack of social awareness and atypical language expression. How facial expressions differ between those on the autism spectrum and neurotypical individuals is not clear. Further, at least half of autistic children have unusual prosody.

Autistic people may also experience difficulties with verbal communication. Differences in communication may be present from the first year of life, and may include delayed onset of babbling, unusual gestures, diminished responsiveness, and vocal patterns that are not synchronized with the caregiver. In the second and third years, autistic children have less frequent and less diverse babbling, consonants, words, and word combinations; their gestures are less often integrated with words. Autistic children are less likely to make requests or share experiences, and are more likely to simply repeat others' words (echolalia). Joint attention seems to be necessary for functional speech, and deficits in joint attention seem to distinguish autistic infants. For example, they may look at a pointing hand instead of the object to which the hand is pointing, and they consistently fail to point at objects in order to comment on or share an experience. Autistic children may have difficulty with imaginative play and with developing symbols into language. Some autistic linguistic behaviors include repetitive or rigid language, and restricted interests in conversation. For example, a child might repeat words or insist on always talking about the same subject. Echolalia may also be present in autistic individuals, for example by responding to a question by repeating the inquiry instead of answering. Language impairment is also common in autistic children, but is not part of a diagnosis. Many autistic children develop language skills at an uneven pace where they easily acquire some aspects of communication, while never fully developing others, such as in some cases of hyperlexia. In some cases, individuals remain completely nonverbal throughout their lives. The CDC estimated that around 40% of autistic children don't speak at all, although the accompanying levels of literacy and nonverbal communication skills vary.