Barnlund's model is an influential transactional model of communication. It was first published by Dean Barnlund in 1970. It is formulated as an attempt to overcome the limitations of earlier models of communication. In this regard, it rejects the idea that communication consists in the transmission of ideas from a sender to a receiver. Instead, it identifies communication with the production of meaning in response to internal and external cues. Barnlund holds that the world and its objects are meaningless in themselves: their meaning depends on people who create meaning and assign it to them. The aim of this process is to reduce uncertainty and arrive at a shared understanding. Meaning is in constant flux since the interpretation habits of people keep changing. Barnlund's model is based on a set of fundamental assumptions holding that communication is dynamic, continuous, circular, irreversible, complex, and unrepeatable.

Cues are of central importance in Barnlund's model. A cue is anything to which one may attribute meaning or which can trigger a response. Barnlund distinguishes between public, private, and behavioral cues. Public cues are available to anyone present in the communicative situation, like a piece of furniture or the smell of antiseptic in a room. Private cues are only accessible to one person, like sounds heard through earphones or a pain in one's chest. Behavioral cues are under the direct control of the communicators, in contrast to public and private cues. They include verbal behavioral cues, like making a remark about the weather, and non-verbal behavioral cues, such as pointing toward an object. Barnlund's model uses arrows going from the communicators to the different types of cues. They represent how each person only gives attention to certain cues by decoding them while they encode and produce behavioral cues in response. Barnlund developed both an intrapersonal and an interpersonal model. The intrapersonal model shows the simpler case where only one person is involved in these processes of decoding and encoding. For the interpersonal model, two people participate. They react not just to public and private cues but also to the behavioral cues the other person produces.

Barnlund's model has been influential as the first major transactional model of communication. This pertains both to its criticism of earlier models and to how it impacted the development of later models. It has been criticized based on the claim that it is not effective for all forms of communication and that it fails to explain how meaning is created.

Dean Barnlund found that previous communication models were missing key components that are part of the communication process and believed communication to be a continuous and simultaneous process challenging long held beliefs of the Linear Model of Communication. This belief led to the creation of his most well known contribution to the field of communication: the Transactional Model of Communication.

Barnlund understands models as attempts to create a simplified picture of an underlying complex reality. This is especially relevant for such a complex process as communication. A good model manages to portray the most salient features at a single glance and may thus assist researchers in their empirical studies. However, this form of simplification also comes with risks like overlooking or distorting factors present in real life. Barnlund's model aims to present the main components of communication in terms of the functions they have.

Barnlund formulated his transactional model of communication as a response to the simplifications and limitations found in various earlier models that take the form of linear transmission models and interaction models. Linear transmission models, like the Shannon–Weaver model, see communication as a linear process: a sender encodes their idea in the form of a message and transmits this message through a channel to a receiver. The receiver has to decode the message in order to understand it. However, as many subsequent communication theorists have pointed out, linear transmission models are too simple to account for all forms of communication. In regular face-to-face conversation, for example, there is usually no designated sender and receiver. Instead, both participants send and receive messages. This problem is partially resolved by interaction models, like Schramm's model. For interaction models, communication is a two-way process. They include a feedback loop through which messages are exchanged back and forth. They are not linear but circular and both participants take turns in encoding and decoding messages. Both linear transmission models and interaction models have in common that they understand communication as the transmission or exchange of meaning.

Barnlund tries to overcome the limitations of these approaches by emphasizing the complexity of communication. He agrees with interaction models that all participants act both as sender and receiver. But he goes beyond them by pointing out that encoding and decoding are not two distinct processes but two simultaneous and interdependent aspects of the same process. He rejects the idea that meaning exists prior to communication. He sees it instead as a product of communication that the communicators assign to the world around them. In his words, communication "is the production of meaning, rather than the production of messages".

For Barnlund, the world and its contents by themselves are meaningless. They only become intelligible and significant because meaning is assigned to them. This ordering process does not happen automatically but is a product of the mind and has to be learned. Barnlund uses the term "communication" in a very wide sense referring to "those acts in which meaning develops within human beings". This involves typical forms of verbal communication, like talking to a friend about an event that just occurred. It also includes non-verbal communication such as pointing somewhere or grimacing in pain. However, since the processes of meaning-making are not restricted to exchanges with other people, there are also forms of communication taking place when a person is all by themselves. The reason is that they decode internal and external stimuli and encode the corresponding behavioral responses. Since these processes do not stop during sensory deprivation and sleep, Barnlund includes even these cases as forms of communication.