A unified approach to quintessence and inflation is investigated with the use of a single scalar field. It is argued that successful potentials have to approximate a combination of exponential and inverse power-law decline in the limit of large values of the scalar field. A class of such potentials is studied analytically and it is found that quintessential inflation is indeed possible. Successful models, not involving more than two natural mass scales, are obtained, which do not require fine-tuning of initial conditions and do not result in eternal acceleration.