The process of learning with understanding was investigated by case study of three male students learning genetics at a tertiary college. Five conclusions regarding the process arise from the study. These conclusions are: (1) Learning outcome is determined by decisions made by the learner. These decisions are influenced by learner perceptions and interpretations. (2) Inadequate learning is due to ineffective decision-making. This ineffective decision-making is associated with specific, recurring learning deficiencies. The main types of deficiency, deficient processing tendencies and misconceptions, cause inadequate performance and preclude learning with understanding. A total of seven tendencies was observed. Each learner applied tendencies idiosyncratically. Tendencies also generated particular misconceptions which further inhibited learning. (3) It takes energy to learn with understanding, or to unlearn a misconception. (4) Learners often are unaware of their deficiencies. This lack of awareness generates inappropriate attitudes. (5) Increased learner awareness of the nature and process of learning changes attitudes and procedures. The major implication of this study relates to promoting self-control of learning. It is proposed that improved learning will result from increasing learner awareness of the nature and process of learning, and by training learners in procedures for enhancing self-evaluation and decision-making.