Peer pressure has a significant influence on teenage smoking. Many anti-smoking organizations claim that teenagers begin their smoking habits due to peer pressure, and cultural influence portrayed by friends. However, one study found that direct pressure to smoke cigarettes did not play a significant part in adolescent smoking. In that study, adolescents also reported low levels of both normative and direct pressure to smoke cigarettes. A similar study showed that individuals play a more active role in starting to smoke than has previously been acknowledged and that social processes other than peer pressure need to be taken into account. Another study's results revealed that peer pressure was significantly associated with smoking behavior across all age and gender cohorts, but that intrapersonal factors were significantly more important to the smoking behavior of 12–13 year-old girls than same-age boys. Within the 14–15 year-old age group, one peer pressure variable emerged as a significantly more important predictor of girls' than boys' smoking. It is debated whether peer pressure or self-selection is a greater cause of adolescent smoking. It is arguable that the reverse of peer-pressure is true, when the majority of peers do not smoke and ostracize those who do.

Nicotine is an addictive stimulant and is one of the main factors leading to continued tobacco smoking. Although the percentage of the nicotine inhaled with tobacco smoke is quite small (most of the substance is destroyed by the heat) it is still sufficient to cause physical and/or psychological dependence. Prior to habituation, teen tobacco smokers often focus on the reinforcing properties of smoking rather than the associated health risks. Because the diseases caused by smoking surface relatively later in life, teenagers do not see their actions as harmful.  As a result, they do not serve to deter smoking given the immediate gratification offered by smoking.  The depressant effect of smoking calms nerves and sometimes allows for increased concentration by decreasing anxiety.  This is another appealing reason and attraction for teens to smoke. Nicotine seems to provide both a stimulant and a depressant effect, and it is likely that the effect it has at any time is determined by the mood of the user, the environment and the circumstances of use. Studies have suggested that low doses have a depressant effect, whilst higher doses have stimulant effect. However, it is impossible to differentiate a drug effect brought on by nicotine use, and the alleviation of nicotine withdrawal.

Somatic and psychological effects of nicotine

The disturbing statistics according to studies by Henningfield and Benowitz, overall nicotine is more addictive than marajuana, caffeine, ethanol, cocaine, and heroin when considering both somatic and psychological dependence. However, due to the stronger withdrawal effects of ethanol, cocaine and heroin, nicotine may have a lower potential for somatic dependence than these substances. A study by Perrine concludes that nicotine's potential for psychological dependency exceeds all other studied drugs - even ethanol, an extremely physically addictive substance with severe withdrawal symptoms that can be fatal. Recent evidence has shown that smoking tobacco increases the release of dopamine in the brain, specifically in the mesolimbic pathway, the same neuro-reward circuit activated by drugs of abuse such as heroin and cocaine. This suggests nicotine use has a pleasurable effect that triggers positive reinforcement which is what many teenagers are lacking in their lives today.