The terms ‘production’ and ‘productivity’ should be distinguished. Production, as defined for limnologists by Thienemann (193lb), is the sum of growth increments of the individuals of a species population, both survivors and non-survivors, through a discrete time period. Generally, production of macroinvertebrates is referable to areal units. Productivity, on the other hand, indicates the trophic nature of a water body or subsystem, often implying the characteristics responsible for low or high productivity (Winberg, 1968). Possibly quantitative assessment of productivity may be achieved most closely with Ohle’s (1956) ‘bioactivity’. One of the purposes of this chapter is to explore the relationship between macroinvertebrate production and lake productivity.