The electoral system is based on the principle of proportional representation. The system's basic outline was established in the constitution of 1920, although significant changes were made in 1970 and 1992. Among other changes, the amendments of 1970 raised the number of seats in the Nationalrat from 165 to 183.

The 1992 reform of the election law, which went into effect in May 1993, alters the electoral system for the Nationalrat in a number of significant ways. It divides the country into nine provincial electoral districts that correspond to the country's nine provinces. These districts contain a further forty-three regional electoral districts. The creation of the small regional electoral districts is intended to foster a greater feeling of connection between voters and those who represent them in parliament. The law also aims to personalize elections by giving voters greater power than before of electing individual candidates of the party of their choice by voting directly for them rather than for the party list of candidates as a whole. This reform may reduce the power of party leaders to impose their preselected candidates on the electorate. The law also modifies vote-counting procedures to ensure that the number of parliamentary seats won by a party will conform more closely with votes cast. Lastly, the law attempts to prevent a proliferation of small parties sitting in the Nationalrat by barring a party from that body if it has not won at least 4 percent of votes cast nationwide. However, a party can be represented in parliament by winning at least one seat in a regional electoral district.

According to the 1992 law, votes in Nationalrat elections are counted in three stages, although a voter casts only one ballot. On this ballot, the voter indicates the party of his choice, and then, if he wishes, he may choose two candidates from this party, one to be elected from the regional voting district and one from the provincial voting district. Votes going to a preferred candidate are called preferential votes. In the first stage of counting votes, the returns from regional voting districts are examined in the second stage, those from provincial voting districts are examined. In these first two stages, the Hare system (see Glossary) is used to determine the proportional allocation of seats. In the third stage of counting votes, candidates on the national party list are allocated seats according to the d'Hondt method (see Glossary).

A party must win a parliamentary seat in the first stage of vote counting in order to win seats in the second and third stages. A candidate who receives preferential votes amounting to at least one-sixth of the votes his party receives wins a parliamentary seat. This is also the case for a candidate who receives preferential votes amounting to at least one-half the electoral quota (Wahlzahl), that is, the number of valid ballots in a voting district divided by the number of parliamentary seats allotted to it. The vote tallying proced337 edures established by the new law mean that about ninety parliamentary seats come from regional voting districts, about sixty-five from provincial voting districts, and roughly twenty-five from the federal level. All persons aged nineteen and over by January 1 of the year in which the election is held are eligible to vote. Voter participation has traditionally been very high. In national elections, it has fallen below 90 percent only once (in 1990, when it stood at 86 percent). Voting always takes place on a Sunday.

Data as of December 1993