The majority of academic literature explicitly or implicitly defines an organisation as “a group of people”. In this paper, we advocate a distinction between the formal social unit (“FSU”) as economic organisation and its (internal) organisation and argue that the latter is essentially the structure (or set) of dynamic relationships between the FSU’s members. Such an approach is supported by the two levels, economic and organisational, of that adaptation of an FSU’s organisation in promoting success in a high-performance economy. A consideration of relationships between members as basic units of organisational analysis elicits the question of which types of relationships (out of many available classifications) are most crucial for attaining the FSU’s goals. By taking firms as the prevailing types of FSUs, we find five (close to Barnard’s view) types or dimensions of relationships, creating the direct instrumental chain of relationships, as being most influential regarding this objective. Due to our awareness that the performance of a firm significantly depends on the quality of the five types of relationships, we suggest that well-defined statistical analyses should be made in order to prove the strength of the influence between the quality of relationships on the direct instrumental chain and the firm’s performance in economic terms. A comparison with similar analyses in which some other groupings of relationships are taken into consideration should prove or negate our assumption.